WO2024006483A1

WO2024006483A1 - Generation of a planar layer on a target surface

Info

Publication number: WO2024006483A1
Application number: PCT/US2023/026649
Authority: WO
Inventors: Abraham SALDIVAR VALDES; Gregory Ferguson BROWN; Benyamin Buller; Joseph Andrew TRALONGO; Alexander John FISHER; William David CHEMELEWSKI
Original assignee: Velo3D, Inc.
Priority date: 2022-07-01
Filing date: 2023-06-29
Publication date: 2024-01-04

Abstract

The present disclosure provides three-dimensional (3D) printing systems, devices, apparatuses, method, and non-transitory computer readable media for generating a planar layer of powder material on a target surface by using a dispenser and an agitator. The target surface can be an exposed surface of a material bed, e.g., utilized for printing at least one 3D object in a printing cycle.

Description

GENERATION OF A PLANAR LAYER ON A TARGET SURFACE

PRIORITY APPLICATIONS

[0001] This Patent Application claims priority from U.S. Provisional Patent Application Serial No. 63/357,901 filed on July 01 , 2022, which is entirely incorporated herein by reference.

BACKGROUND

[0002] Three-dimensional (3D) printing (e.g., additive manufacturing) is a process for making a three-dimensional object of any shape from a design. The design may be in the form of a data source such as an electronic data source, or may be in the form of a hard copy. The hard copy may be a two-dimensional representation of a 3D object. The data source may be an electronic 3D model. 3D printing may be accomplished through an additive process in which successive layers of material are laid down one on top of another. This process may be controlled (e.g., computer controlled, manually controlled, or both). A 3D printer can be an industrial robot.

[0003] 3D printing can generate custom parts. A variety of materials can be used in a 3D printing process including elemental metal, metal alloy, ceramic, an allotrope of elemental carbon, or polymeric material. In some 3D printing processes (e.g., additive manufacturing), a first layer of hardened material is formed (e.g., by welding powder), and thereafter successive layers of hardened material are added one by one, wherein each new layer of hardened material is added on a pre-formed layer of hardened material, until the entire designed three-dimensional structure (3D object) is layer-wise materialized.

[0004] 3D models may be created with a computer aided design package, via 3D scanner, or manually. The manual modeling process of preparing geometric data for 3D computer graphics may be similar to plastic arts, such as sculpting or animating. 3D scanning is a process of analyzing and collecting digital data on the shape and appearance of a real object (e.g., real-life object). Based at least in part on this data, 3D models of the scanned object can be produced. [0005] A number of 3D printing processes are currently available. They may differ in the manner layers are deposited to create the materialized 3D structure (e.g., hardened 3D structure). They may vary in the material or materials that are used to materialize the designed 3D object. Some methods melt, sinter, or soften material to produce the layers that form the 3D object. Examples for 3D printing methods include selective laser melting (SLM), selective laser sintering (SLS), direct metal laser sintering (DMLS) or fused deposition modeling (FDM). Other methods cure liquid materials using different technologies such as stereo lithography (SLA). In the method of laminated object manufacturing (LOM), thin layers (made inter alia of paper, polymer, or metal) are cut to shape and joined together.

[0006] At times, dispensing a requested thickness of planar powder layer during a recoating process involves an initial dispense operation followed by a removal operation as part of a 3D printing process. The initial dispense operation may dispense a powder layer substantially thicker (e.g., 30x-40x) than the requested thickness. One drawback of this process is removal of a large portion (e.g., at least about 80% or 90%) of the powder dispensed, to generate the planar powder layer with the requested thickness. Thus, a large of volume excess powder is not utilized to generate a layer of the powder bed. The excess of powder may be recycled and utilized in the generation of at least one other layer of powder material in this or in another powder bed. During the recoating and/or recycling process, the excess of power may become exposed the atmosphere in the 3D printing system, e.g., the atmosphere in the processing chamber. Such atmosphere may include reactive agent(s) such as humidity and/or oxygen The large volume of recycled powder can put stress on the recycling system and/or on the powder conveyance system that may include separators, sieves, pumps, conveyors, and/or the like. Exposure to the 3D printer’s atmosphere having the reactive agent(s) can result in their reaction with the particulate matter of the powder material (e.g., with reactive species on the surface of the powder particles). The reaction may cause a degradation of the powder material (e.g., passivation of the powder material) and/or resulting printed parts that are faulty (e.g., comprising defect(s)). The more the powder material is exposed to the reactive species (e.g., during repeated recycling and/or recoating operations), the greater chance there will be for reaction with the reactive species.

SUMMARY

[0007] In some aspects, the present disclosure resolves the aforementioned hardships. In an aspect, the present disclosure comprises utilizing a recoater comprising (a) a dispenser and (b) a remover. For example, a recoater configured to apply a first layer of powder material to a (e.g., planar) target surface such as an exposed surface of a powder bed (i) where the target surface includes portions of 3D object(s) that protrude from the target surface, where a thickness of the first layer is smaller than a maximal height of the protrusion(s) from the target surface, (ii) where a deviation (e.g., standard deviation) from planarity of the exposed surface after removal of a portion of powder is lower than the deviation (e.g., standard deviation) from planarity of the exposed surface after dispensing of the first layer, (iii) where a closest distance between the target surface and the recoater is larger than a thickness of the first layer, (iv) where the dispenser dispenses a first layer having a first thickness, and where the remover removes material from the first layer resulting in a second layer having a second thickness that is thinner than the first thickness, (v) where the agitator is mechanically or sonically agitated and where the agitator is isolated from the dispenser , (vi) where a transducer of the agitator is disposed outside of a processing chamber enclosing the first layer, (vii) where a dew point of a atmosphere in the processing chamber is (a) below a level in which the powder particles absorb water such that they become reactive under conditions of the 3D printing and/or is sufficient to cause measurable defects in the 3D object printed from the powder particles, and (b) above a level of humidity below which the powder agglomerates, e.g., electrostatically, (viii) the dispenser includes an agitator coupled to a gate of the exit port of the dispenser that facilitates in increasing a fluidity of the powder material to facilitate its egress (e.g., exit) from the dispenser, or (x) any combination of (i)-(viii).

[0008] In another aspect, a device for generating a planar layer of powder material, the device comprises: a dispenser comprises (I) a reservoir configured to accommodate powder material and (II) an exit port, the dispenser being configured to dispense at least a first portion of the powder material through the exit port; and an agitator that is operatively coupled to, or that is part of, the dispenser, the agitator being configured to induce an increase of a flow rate of the powder material from the exit port of the dispenser towards a (e.g., planar) target surface, the device being configured to generate a first layer of powder material on the target surface, the first layer having a first exposed surface that is substantially planar according to a first central tendency of planarity, and the first layer having a second central tendency of a thickness.

[0009] In another aspect, a device for generating a planar layer of powder material, the device comprises: a dispenser comprises (I) a reservoir configured to accommodate powder material and (II) an exit port, the dispenser being configured to dispense at least a first portion of the powder material through the exit port; and an agitator that is operatively coupled to, or that is part of, the dispenser, the agitator being configured to induce an increase of a flow rate of the powder material from the exit port of the dispenser towards a (e.g., planar) target surface, the device being configured to generate a first layer of powder material on the target surface, the first layer having a first exposed surface that is substantially planar according to a first central tendency of planarity, and the first layer having a second central tendency of a thickness, wherein: (A) the target surface includes one or more protrusions from the target surface, the one or more protrusions being of one or more three-dimensional objects, and wherein the second central tendency of the thickness of the first layer is smaller than a maximal height (e.g., vertical distance) of the one or more protrusions from the target surface, (B) the device further comprises a remover configured to remove a second portion of powder material from the first layer to generate a second layer of powder material having a second exposed surface that is substantially planar according to a third central tendency of planarity, the third central tendency of planarity being of the same type as the first central tendency of planarity, and wherein the third central tendency of planarity is smaller than the first central tendency of planarity of the first layer such that the third central tendency of planarity is indicative of a more planar surface than the first tendency of planarity, (C) the second layer has a thickness having a fourth central tendency of thickness of the same type as the second central tendency of thickness, wherein during operation of the device, a closest distance between the target surface and the device is larger than (a) the second central tendency of thickness of the first layer and/or (b) the fourth central tendency of thickness of the second layer, (D) the agitator is separated from the dispenser, (E) the agitator is operatively coupled to a panel that is operatively coupled to, or that is part of, the dispenser, the panel being arranged with respect to the exit port of the dispenser, the panel being configured to (c) in the first operating state, restrict flow of the powder material through the exit port of the dispenser and (d) in the second operating state, allow the flow of the powder material from the exit port of the dispenser towards the target surface, (F) a transducer of the agitator is disposed outside of a processing chamber that encloses the first layer, (G) the device is configured to operate at an interior atmosphere of the processing chamber, and wherein the a dew point of an interior atmosphere of the processing chamber is (III) above a level of humidity at or below which the powder material agglomerates, and (IV) below a level in which the powder material absorbs water (e) such that the powder material becomes reactive under conditions of a three-dimensional printing process utilizing the powder material and/or (f) such that the absorbed water on the powder material is sufficient to cause a measurable defect in the one or more three-dimensional objects printed from the powder material, or (H) any combination of (A)-(G). In some embodiments, the device is configured to operatively coupled to a recycling system that (i) recycles at least a fraction of the second portion of powder material removed by the remover and/or (ii) provides at least a portion of the powder material utilized by the dispenser. In some embodiments, the first central tendency of planarity and the second central tendency of planarity are each measured as mean, median, or mode. In some embodiments, the first central tendency of planarity and the second central tendency of planarity are each a surface roughness measured as (i) an arithmetic average of a surface roughness profile (R_a), (ii) an arithmetic average of peak-to-valley height of a surface roughness profile (R_z), or (iii) a root mean square (RMS) average. In some embodiments, the third central tendency of thickness and the fourth central tendency of thickness are each measured as mean, median, or mode. In some embodiments, the third central tendency of thickness and the fourth central tendency of thickness are each measured as (i) an arithmetic average of a surface roughness profile (R_a~), (ii) an arithmetic average of peak-to-valley height of a surface roughness profile (R_z), or (iii) a root mean square (RMS) average. In some embodiments, at least during use of the device, the device is configured for lateral translation along the target surface. In some embodiments, the agitator is configured to increase the flow at least in part by allowing the flow. In some embodiments, the agitator is configured to increase the flow at least in part by providing energy to the powder material to increase their mobility and/or flowability. In some embodiments, the agitator is configured to restrict the flow at least in part by stopping the flow. In some embodiments, the agitator is configured for mechanical and/or sonic agitation. In some embodiments, the device is configured for sonic agitation at least in part by being configured for ultrasonic agitation. In some embodiments, the target surface is an exposed surface of a powder bed in which the one or more three-dimensional objects were generated, and wherein the device is configured to dispense the planar layer on the exposed surface of the powder bed. In some embodiments, the one or more three-dimensional objects comprise three-dimensional objects generated by three-dimensional printing methodology. In some embodiments, the device is configured to operate as part of a three-dimensional printing system for printing three- dimensional objects such as the one or more three-dimensional objects. In some embodiments, the powder material comprises elemental metal, metal alloy, a ceramic, or an allotrope of elemental carbon. In some embodiments, the powder material comprises titanium, stainless steel, Inconel, or copper. In some embodiments, the device is configured to operatively couple to an energy source configured to generate an energy beam utilized in printing the one or more three-dimensional objects using three-dimensional printing. In some embodiments, the increase of the flow rate comprises an increase of at least about 0.2 cubic centimeters per second (cm³/sec), 0.4 cm³/sec, 0.5 cm³/sec, 1 cm³/sec, or 2 cm³/sec. In some embodiments, the reservoir is configured to retain powder material. In some embodiments, in the first operating state, the agitator is configured to induce the increase of the flow rate of the powder material from a zero, or a substantially zero, flow rate. In some embodiments, in the second operating state, the agitator is configured to cease, or substantially cease, inducing the flow rate of the powder material through the exit port of the dispenser. In some embodiments, the device is configured to (i) in a first operating state, induce the increase of the flow rate of the powder material from the exit port of the dispenser towards the target surface and (ii) in a second operating state, reduce inducing the flow rate of the powder material through the exit port of the dispenser. In some embodiments, the second central tendency of the thickness is from about 30 microns to about 500 microns. In some embodiments, the first central tendency of planarity of the first layer is from about 15% to about 65% of the second central tendency of the thickness. In some embodiments, the target surface includes one or more protrusions from the target surface, the one or more protrusions being of the one or more three-dimensional objects, and wherein the second central tendency of the thickness of the first layer is smaller than a maximal height of the one or more protrusions from the target surface. In some embodiments, the target surface is an exposed surface of a powder bed from which the one or more three-dimensional objects protrude, wherein device is configured to generate the powder bed that includes the first layer of powder material, wherein the powder bed is supported by a building platform, and wherein the one or more three-dimensional objects are disconnected from the platform. In some embodiments, the one or more three-dimensional objects are devoid of auxiliary supports. In some embodiments, the maximal height (e.g., vertical height) of the one or more protrusions from the target surface is smaller than (i) a distance between the device and the target surface and/or (ii) a second central tendency of thickness of the first layer. In some embodiments, a difference between the maximal height of the one or more protrusions from the target surface and the second central tendency of layer thickness of the first layer is from about 1 mm to about 20 mm. In some embodiments, maximal height of the one or more protrusions from the target surface is larger than the first central tendency of planarity of the first layer. In some embodiments, the device is operatively coupled to a detector configured to detect a height of the one or more protrusions from the target surface, which detector comprises an optical sensor and a projected image. In some embodiments, the optical sensor comprises a camera. In some embodiments, the projected image comprises a repeating pattern. In some embodiments, the detector includes, or is operatively coupled to, an image processor. In some embodiments, the one or more protrusions result at least in part from deformation of the one or more three- dimensional objects during their generation. In some embodiments, the device further comprises a remover configured to remove a second portion of powder material from the first layer to generate a second layer of powder material having a second exposed surface that is substantially planar according to a third central tendency of planarity, the third central tendency of planarity being of the same type as the first central tendency of planarity, and wherein the third central tendency of planarity is smaller than the first central tendency of planarity of the first layer such that the third central tendency of planarity is indicative of a more planar surface than the first tendency of planarity. In some embodiments, the remover is configured to remove the second portion of powder material from the first layer, the second layer being at most about 75% of the first layer by volume and/or by weight. In some embodiments, the remover is configured to remove a volume of the second portion of powder material from the first layer that is at least about half of the first layer by volume and/or by weight. In some embodiments, the third central tendency of planarity and the first central tendency of planarity being of the same type comprising: mean, median, or mode. In some embodiments, the remover is configured to remove at least about 80%, 70%, or 60% of the powder material dispensed by the dispenser by volume and/or by weight. In some embodiments, the second portion is at least about 80%, 70%, or 60% of the first portion by volume and/or by weight. In some embodiments, the third central tendency of planarity is at most about 70% of the first central tendency of planarity of the first layer. In some embodiments, the third central tendency of planarity is at least about half the first central tendency of planarity of the first layer. In some embodiments, the remover comprises a nozzle having an entry port through which the second portion of powder material removed enters the remover. In some embodiments, the remover comprises a suction mechanism. In some embodiments, the remover is configured to operatively couple to an attractive force source sufficient to attract the powder material. In some embodiments, the force source comprises a magnetic, electric, or vacuum source. In some embodiments, the force source comprises a vacuum source. In some embodiments, the remover comprises a roller configured to propel the powder material away from the first layer of powder material. In some embodiments, the roller is configured to generate a gas flow that at least in part propels the powder material away from the first layer of powder material. In some embodiments, a volume of the second portion of powder is at least 60% of the volume of the first portion of powder. In some embodiments, a volume of the second portion of powder is at most 50% of the volume of the first portion of powder. In some embodiments, the device comprises a mount, and wherein the remover and the dispenser are mounted on a mount. In some embodiments, the remover is separated from the dispenser by a gap. In some embodiments, at least during use of the device, the mount is configured to laterally translate along the target surface. In some embodiments, at least during use of the device, the remover is configured to laterally translate along the target surface. In some embodiments, the lateral translation of the remover is coordinated with the lateral translation of the dispenser. In some embodiments, the dispenser is configured to dispense the powder material when translating in a first direction, and wherein the remover is configured to translate the powder material when translating in a second direction opposite the first direction. In some embodiments, the configuration comprises a disposition of the exit opening of the dispenser and an entrance port (e.g., entrance opening) of the remover with respect to the first direction and/or the second direction. In some embodiments, the configuration comprises a disposition of the agitator with respect to the first direction and/or the second direction. In some embodiments, the dispenser comprises at least one panel onto which the powder material is dispensed on its way from the exit port to the target surface, and wherein the configuration comprises a disposition of the at least one panel with respect to the first direction and/or the second direction. In some embodiments, the at least one panel comprises an orifice, and wherein the configuration comprises a disposition of the orifice with respect to the at least one panel and to the first direction and/or the second direction. In some embodiments, the dispenser is configured to dispense the powder material when translating in a first direction, and wherein the remover is configured to translate the powder material when translating in the first direction. In some embodiments, the remover is configured to remove after the dispenser dispenses. In some embodiments, the configuration comprises a disposition of the exit opening of the dispenser and the entrance port of the remover with respect to the first direction. In some embodiments, the configuration comprises a disposition of the agitator with respect to the first direction and/or the second direction. In some embodiments, the dispenser comprises at least one panel onto which the powder material is dispensed on its way from the exit port to the target surface, and wherein the configuration comprises a disposition of the at least one panel with respect to the first direction and/or the second direction. In some embodiments, the at least one panel comprises an orifice, and wherein the configuration comprises a disposition of the orifice with respect to the at least one panel and to the first direction. In some embodiments, the second layer has a thickness having a fourth central tendency of thickness of the same type as the second central tendency, wherein during operation of the device, the closest distance between the target surface and the device is larger than (a) the second central tendency of thickness of the first layer and/or (b) the fourth central tendency of thickness of the second layer. In some embodiments, the device further comprises a remover configured to remove the second portion of powder material from the first layer to generate the second layer of powder material having the fourth central tendency of thickness. In some embodiments, the fourth central tendency of thickness of the second layer is smaller than the second central tendency of thickness of the first layer. In some embodiments, the fourth central tendency of thickness of the second layer is at least about 45% of the second central tendency of thickness of the first layer. In some embodiments, the fourth central tendency of thickness of the second layer is at most about half of the second central tendency of thickness of the first layer. In some embodiments, the fourth central tendency of thickness of the second layer is at most about 100 microns. In some embodiments, the third central tendency of planarity of the second layer is at most about half of the first central tendency of planarity of the first layer. In some embodiments, the third central tendency of planarity of the second layer is smaller than the fourth central tendency of thickness of the second layer. In some embodiments, the closest distance between the target surface and the device is at least 1 millimeter. In some embodiments, the closest distance between the target surface and the device is at least 3 times the second central tendency of thickness of the second layer. In some embodiments, the closest distance between the target surface and the device is at least about 100% larger than the second central tendency of thickness of the second layer. In some embodiments, the agitator is separated from the dispenser. In some embodiments, the agitator is included in the panel. In some embodiments, the panel comprises a waveguide operatively coupled to the transducer. In some embodiments, the waveguide comprises a sonic waveguide. In some embodiments, the sonic waveguide is an ultrasonic waveguide. In some embodiments, the waveguide is separated sonically with respect to the dispenser. In some embodiments, the panel is separated from the exit port of the dispenser by a gap. In some embodiments, the panel is affixed to the dispenser by an absorptive material having an acoustic impedance smaller than an acoustic impedance of a material of the panel. In some embodiments, the acoustic impedance of the absorptive material is at least about an order of magnitude smaller than the acoustic impedance of the material of the panel. In some embodiments, the panel comprises mechanical supports, wherein every two immediately adjacent mechanical supports are separated by a distance, the mechanical supports configured to affix the panel to a body of the dispenser, and wherein every two immediately adjacent mechanical supports are devoid of additional one or more mechanical support disposed in the distance. In some embodiments, the mechanical supports are configured such that a vibrational frequency of a sonic wave is an integer multiplier of the distance between every two immediately adjacent mechanical supports. In some embodiments, the mechanical supports are configured such that a vibrational frequency of the sonic wave is not quenched or not substantially quenched while propagating in the panel. In some embodiments, the mechanical supports are arranged in a single file. In some embodiments, the mechanical supports are arranged with respect to a length of the panel at null points of a standing wave propagating in the panel. In some embodiments, the panel is separated from the exit port by a gap having a fundamental length scale such that an angle of repose of the powder material exiting the dispenser through the exit port and disposed onto a surface of the panel significantly restricts a material fall of the powder material off of an edge of the panel, the surface of the panel facing the exit port. In some embodiments, the angle of repose of the powder material from exiting the dispenser through the exit port and disposed onto the surface of the panel stops the material fall of the powder material off of the edge of the panel. In some embodiments, the panel is separated from the exit port by a gap having a fundamental length scale such that an angle of repose of the powder material exiting the dispenser through the exit port and disposed onto a surface of the panel facilitate retention of the powder material on the surface of the panel that faces the exit port. In some embodiments, the gap has a fundamental length scale that is substantially zero. In some embodiments, a fundamental length scale of the panel is 3 to 5 times a fundamental length scale of the gap. In some embodiments, the panel is arranged with respect to the exit port of the dispenser, the panel being configured to (c) in the first operating state, restrict flow of the powder material through the exit port of the dispenser and (d) in the second operating state, allow the flow of the powder material from the exit port of the dispenser towards the target surface. In some embodiments, the panel is arranged with respect to the exit port of the dispenser, such that, in the first operating state, powder material of the first portion of powder material is disposed on a surface of the panel. In some embodiments, the panel is arranged with respect to the exit port of the dispenser, such that, in the first operating state, the powder material disposed on the surface of the panel forms an angle of repose with respect to the surface of the panel. In some embodiments, the panel is arranged with respect to the exit port of the dispenser, such that, in the first operating state, a lateral spread of the portion of powder material disposed on the surface of the panel is less than about half a fundamental length scale of the panel. In some embodiments, the panel is arranged with respect to the exit port of the dispenser, such that, in the first operating state, a lateral spread of the portion of powder disposed on the surface of the panel is at least about 3x smaller than a fundamental length scale of the panel. In some embodiments, the panel is arranged with respect to the exit port of the dispenser, such that, in the first operating state, the panel is configured to restrict substantially zero flow of powder material through the exit port of the dispenser. In some embodiments, the panel is arranged with respect to the exit port of the dispenser, such that, in the second operating state, the panel is configured fluidize the powder material to allow the flow from the exit port of the dispenser towards the target surface. In some embodiments, the panel is arranged with respect to the exit port of the dispenser, such that, in the second operating state, the fluidized powder material flows over edges of the panel. In some embodiments, the panel is arranged with respect to the exit port of the dispenser, such that, in the second operating state, the fluidized powder material flows over one or more of the edges of the panel. In some embodiments, the panel further comprises a restriction configured to restrict, or stop, a flow of fluidized powder material off one or more of the edges of the panel. In some embodiments, the restriction comprises a lip. In some embodiments, the panel comprises an orifice, and wherein, in the second operating state, the orifice is configured to facilitate flow of the powder material through the orifice towards the target surface. In some embodiments, the orifice is a precision orifice having a fundamental length scale similar to a fundamental length scale of the exit port of the reservoir. In some embodiments, the orifice is a precision orifice having a fundamental length scale larger than a fundamental length scale of a particle of the powder material and of or smaller than the fundamental length scale of the exit opening. In some embodiments, the panel is aligned with the exit opening, and wherein the orifice is offset from a center point of the panel that overlaps with a center point of the exit port of the dispenser, such that (i) in the first operating state, the panel is configured to restrict, or stop, flow of the powder material through orifice and (ii) in the second operating state, the powder material flows through the orifice. In some embodiments, the orifice is offset along an XY plane parallel to a surface of the panel opposing the exit port of the dispenser. In some embodiments, the agitator is configured such that when powder material is disposed within a body of the reservoir, at least a portion of the agitator disposed within the reservoir is surrounded by the powder material. In some embodiments, the agitator is physically separated from the body of the reservoir. In some embodiments, the agitator is physically separated from the body of the dispenser. In some embodiments, the agitator is configured to measure a level of the powder material in the reservoir. In some embodiments, the agitator is configured to measure a level of the powder material in the reservoir during operation of the dispenser. In some embodiments, the agitator comprises an outer member enclosing an inner member. In some embodiments, the outer member comprises perforations to facilitate flow of the powder material into the outer member and out of the outer member, and wherein the inner member comprises a waveguide. In some embodiments, the device further comprises an absorber operatively coupled to, or that is part of the agitator, the absorber being arranged with respect to the agitator to substantially minimize a standing wave propagating within the agitator. In some embodiments, substantially minimizing the standing wave propagating within the agitator comprises dampening an amplitude of the standing wave propagating over a length of the agitator. In some embodiments, the damping of the standing wave is to about zero. In some embodiments, substantially minimizing the standing wave propagating within the agitator comprises minimizing the standing wave such that the standing wave ratio is substantially one. In some embodiments, the absorber is included in an acoustic black hole, also known as a vibration acoustic black hole, and is abbreviated herein as “ABH”. The ABH may comprise an inhomogeneity in the waveguide, e.g., comprising geometric (e.g., shape), or material inhomogeneity of the waveguide panel. The ABH may be an in homogenous portion of the waveguide, e.g., at a terminal of the waveguide. In an example, the ABH is a narrowing wedge ending portion of an otherwise homogenous panel acting as a waveguide. The material inhomogeneity may comprise variation in stiffness, and/or in chemical composition. In some embodiments, a material of the absorber is a substantial impedance matched to a material of the agitator. In some embodiments, the absorber comprises roughening at least a portion of a surface of the agitator. In some embodiments, the absorber comprises a volume of powder material in contact with at least a portion of the agitator. In some embodiments, the agitator comprises a tapered portion. In some embodiments, the agitator comprises a curved portion. In some embodiments, the agitator is operatively coupled to the panel that is operatively coupled to, or that is part of, the dispenser, the panel being arranged with respect to the exit port of the dispenser, the panel being configured to (c) in the first operating state, restrict flow of the powder material through the exit port of the dispenser and (d) in the second operating state, allow the flow of the powder material from the exit port of the dispenser towards the target surface. In some embodiments, the panel is arranged with respect to the exit port of the dispenser to at least partially obstruct the exit port in the first operating state. In some embodiments, the panel is arranged with respect to the exit port of the dispenser such that in a first operating state, when a portion of the powder material exits the exit port towards the target surface, it is disposed on a surface of the panel to form an angle of repose and fill the exit port, the surface of the panel facing the exit port. In some embodiments, the agitator is disposed in an interior cavity of the dispenser. In some embodiments, the agitator is disposed on an exterior of the dispenser. In some embodiments, the panel is a first gate, and wherein the device further comprises a second gate that is operatively coupled to, or that is part of, the dispenser, the second gate being arranged with respect to the exit port of the dispenser, the second gate being configured to (e) in the first operating state, restrict flow of the powder material through the exit port of the dispenser and (f) in the second operating state, increase the flow of the powder material from the exit port of the dispenser towards a target surface. In some embodiments, the second gate is configured to increase the flow at least in part by allowing the flow in the second operating state. In some embodiments, the second gate is configured to restrict the flow at least in part by stopping the flow in the first operating state. In some embodiments, the second gate is arranged with respect to the exit port of the dispenser such that a portion of the powder material is disposed on a surface of the second gate and forms an angle of repose on the surface of the second gate in the first operating state. In some embodiments, the second gate is a mechanical gate comprising a shutter, flap, or iris. In some embodiments, the agitator is operatively coupled to the first gate or to the second gate. In some embodiments, the dispenser is operatively coupled to at least one other agitator. In some embodiments, the transducer of the agitator is disposed outside of the processing chamber enclosing the first layer. In some embodiments, the transducer is isolated from a body of the dispenser. In some embodiments, the transducer is isolated from an interior atmosphere of the processing chamber. In some embodiments, the transducer is sealed from an interior atmosphere of the processing chamber by a seal. In some embodiments, the seal comprises (i) a hermetic seal, (ii) a gas tight seal, (iii) a seal separating the transducer from the powder material, or (iv) a seal separating the transducer from debris. In some embodiments, the debris comprises soot, spatter, or splatter. In some embodiments, the debris is a byproduct of three- dimensional printing taking place in the processing chamber to form the one or more three- dimensional objects. In some embodiments, the transducer is configured to operatively couple to a power source at least in part by (I) having a power socket and/or (II) being configured for wireless power transfer using inductive charging. In some embodiments, the device is configured to operate at an interior atmosphere of the processing chamber, and wherein the dew point of the interior atmosphere of the processing chamber is (III) above the level of humidity at or below which the powder material agglomerates, and (IV) below the level in which the powder material absorbs water (e) such that the powder material becomes reactive under conditions of the three-dimensional printing process utilizing the powder material and/or (f) such that the absorbed water on the powder material is sufficient to cause the measurable defect in the three-dimensional object printed from the powder material. In some embodiments, the interior atmosphere of the processing chamber is maintained to have a reactive species below a concentration of a reactive species ambient atmosphere external to the processing chamber, the reactive species being reactive with the powder material under conditions of three-dimensional printing for printing the one or more three-dimensional object. In some embodiments, the reactive species comprise oxygen or water. In some embodiments, the dew point of the interior atmosphere of the processing chamber is above the level of humidity at or below which the powder material agglomerates. In some embodiments, the dew point of the interior atmosphere of the processing chamber is above the level of humidity at or below which the powder material agglomerates electrostatically and/or spontaneously. In some embodiments, the dew point of the interior atmosphere of the processing chamber is at or below the level in which the powder material absorbs water such that the powder material becomes reactive under condition of three-dimensional printing process utilizing the powder material. In some embodiments, the dew point of the interior atmosphere of the processing chamber is at or below the level in which the powder material absorbs water such that the powder material becomes reactive with the absorbed water under condition of three-dimensional printing process utilizing the powder material. In some embodiments, the dew point of the interior atmosphere of the processing chamber is at or below the level in which the powder material absorbs water such that the absorbed water on the powder material is sufficient to cause the measurable defect in the three- dimensional object printing from the powder material. In some embodiments, the dew point of the interior atmosphere of the processing chamber is from about -65 degrees Celsius (°C) to about -40 °C. In some embodiments, the interior atmosphere is different in at least one characteristic from an ambient atmosphere external to the processing chamber. In some embodiments, the at least one characteristic comprises pressure, temperature, reactive agent level (e.g., oxygen, humidity), inert gas level (e.g., Nobel gas level), flow rate, or flow direction. In some embodiments, a pressure of the interior atmosphere of the processing chamber comprises at least about 10 kilo-Pascals above the ambient atmosphere external to the processing chamber. In some embodiments, the interior atmosphere of the processing chamber is maintained above ambient atmosphere external to the processing chamber. In some embodiments, an oxygen content in the powder being about 0.5% weight percent or less. In some embodiments, an oxygen content in the powder being about 1500 ppm or less. In some embodiments, an oxygen content in the powder being about 1000 to about 250 ppm. In some embodiments, a humidification of the processing chamber being less than about 1000 ppm. In some embodiments, an oxygen level of the processing chamber being from about 0.5 ppm to about 1100 ppm.

[0010] In another aspect, an apparatus for generating a planar layer of powder material, the apparatus comprises at least one controller configured to (i) operatively couple to any of the devices above; and (ii) direct the device to implement at least one operation associated with the device comprises direct the device to generate the planar layer. In an example, an apparatus for generating a planar layer of powder material, the apparatus comprises: at least one controller configured to: (i) operatively couple to a dispenser comprises (I) an exit port and (II) a reservoir configured to accommodate powder material; (ii) operatively couple to an agitator that is operatively coupled to, or that is part of, the dispenser; and (iii) direct the dispenser to dispense at least a first portion of powder material through the exit port of the dispenser to generate a first layer having a first exposed surface that is substantially planar according to a first central tendency of planarity, the first exposed surface having a second central tendency of thickness of the first layer, the at least one controller being configured to direct the dispenser to dispense at least in part by directing the agitator to induce an increase of a flow rate of the powder material from the exit port of the dispenser towards a (e.g., planar) target surface, wherein (A) the target surface includes one or more protrusions from the target surface, the one or more protrusions being of one or more three-dimensional objects, and wherein the second central tendency of the thickness of the first layer is smaller than a maximal height (e.g., vertical distance) of the one or more protrusions from the target surface, (B) the at least one controller being configured to operatively couple to a remover and configured to direct the remover to remove a second portion of powder material from the first layer to generate a second layer of powder material having a second exposed surface that is substantially planar according to a third central tendency of planarity, the third central tendency of planarity being of the same type as the first central tendency of planarity, and wherein the third central tendency of planarity is smaller than the first central tendency of planarity of the first layer such that the third central tendency of planarity is indicative of a more planar surface than the first tendency of planarity, (C) wherein the second layer has a thickness having a fourth central tendency of thickness of the same type as the second central tendency, wherein during operation of the dispenser, a closest distance between the target surface and the dispenser is larger than (a) the second central tendency of thickness of the first layer and/or (b) the fourth central tendency of thickness of the second layer, (D) the agitator is separated from the dispenser, (E) the at least one controller being operatively coupled to a panel, where the agitator is operatively coupled to the panel that is operatively coupled to, or that is part of, the dispenser, the panel being arranged with respect to the exit port of the dispenser, the at least one controller being configured to direct the panel to (c) in the first operating state, restrict flow of the powder material through the exit port of the dispenser and (d) in the second operating state, allow the flow of the powder material from the exit port of the dispenser towards a target surface, (F) a transducer of the agitator is disposed outside of a processing chamber enclosing the first layer, (G) the controller being configured to control a dew point of an interior atmosphere of the processing chamber (III) above a level of humidity at or below which the powder material agglomerates, and/or (IV) below a level in which the powder material absorbs water (e) such that the powder material becomes reactive under conditions of a three-dimensional printing process utilizing the powder material and/or (f) such that the absorbed water on the powder material is sufficient to cause a measurable defect in a three- dimensional object printed from the powder material, or (H) any combination of (A)-(G). In some embodiments, the at least one controller being configured to operatively couple to a power source at least in part by (I) having a power socket and/or (II) being configured for wireless power transfer using inductive charging. In some embodiments, the at least one controller is included in, or comprises, a hierarchical control system. In some embodiments, the hierarchical control system comprises at least three hierarchical control levels. In some embodiments, the at least one controller is included in a control system configured to control a three-dimensional printer that prints the one or more three-dimensional objects. In some embodiments, the device is a component of a three-dimensional printing system, and wherein the at least one controller is configured to (i) operatively couple to an other component of the three-dimensional printing system and (ii) direct operation of the other component. In some embodiments, the at least one controller is configured to direct operation of the other component at least in part for participation of the other component in three-dimensional printing. In some embodiments, the at least one operation is operations, wherein the at least one controller is controllers, and wherein at least two of the operations are directed or are executed by different controllers. In some embodiments, the at least one operation is operations, and wherein at least two of the operations are executed or are directed by the same controller of the at least one controller. [0011] In another aspect, non-transitory computer readable program instructions that, when executed by one or more processors operatively coupled to any of the devices above, implement one or more operations associated with the device comprises directing the device to generate the planar layer. In an example, non-transitory computer readable program instructions for generating a planar layer of powder material, the non-transitory computer readable program instructions, when read by one or more processors operatively coupled to a dispenser and to an agitator, cause the one or more processors to execute operations comprises: directing the dispenser to dispense at least a first portion of powder material through an exit port of the dispenser to generate a first layer having a first exposed surface that is substantially planar according to a first central tendency of planarity, the first exposed surface having a second central tendency of thickness of the first layer, the dispenser comprises (I) the exit port and (II) a reservoir configured to accommodate powder material, the directing of the dispenser to dispense comprises: using at least in part the agitator to increase a flow rate of the powder material from the exit port of the dispenser towards a (e.g., planar) target surface, the agitator being operatively coupled to, or being part of, the dispenser, wherein: (A) the target surface includes one or more protrusions from the target surface, the one or more protrusions being of one or more three-dimensional objects, and wherein the second central tendency of the thickness of the first layer is smaller than a maximal height of the one or more protrusions from the target surface, (B) the one or more processors are operatively coupled to a remover, and wherein the non-transitory computer readable program instructions, when read by the one or more processors operatively coupled to the remover, cause the one or more processors execute operations comprises: directing the remover to remove a second portion of powder material from the first layer to generate a second layer of powder material having a second exposed surface that is substantially planar according to a third central tendency of planarity, the third central tendency of planarity being of the same type as the first central tendency of planarity, and wherein the third central tendency of planarity is smaller than first central tendency of planarity of the first layer such that the third central tendency of planarity is indicative of a more planar surface than the first tendency of planarity, (C) the second layer has a thickness having a fourth central tendency of thickness of the same type as the second central tendency of thickness of the first layer, wherein during operation of the dispenser, a closest distance between the target surface and the dispenser is larger than (a) the second central tendency of thickness of the first layer and/or (b) the fourth central tendency of thickness of the second layer, (D) the agitator is separated from the dispenser, (E) when the agitator is operatively coupled to a panel that is operatively coupled to, or that is part of, the dispenser, the panel being arranged with respect to the exit port of the dispenser, the one or more processors execute operations comprises: instructing the panel to (c) in the first operating state, restrict flow of the powder material through the exit port of the dispenser and (d) in the second operating state, allow the flow of the powder material from the exit port of the dispenser towards a target surface, (F) a transducer of the agitator is disposed outside of a processing chamber enclosing the first layer, (G) the operations further comprise controlling a dew point of an interior atmosphere of the processing chamber (III) above a level of humidity at or below which the powder material agglomerates, and/or (IV) below a level in which the powder material absorbs water (e) such that the powder material becomes reactive under conditions of a three-dimensional printing process utilizing the powder material and/or (f) such that the absorbed water on the powder material is sufficient to cause a measurable defect in a three-dimensional object printed from the powder material, or (H) any combination of (A)-(G). In some embodiments, the one or more processors are included in, or comprise, a hierarchical control system. In some embodiments, the hierarchical control system comprises at least three hierarchical control levels. In some embodiments, the one or more operations comprise printing the one or more three-dimensional objects. In some embodiments, the device is a component of a three-dimensional printing system, and where the one or more processors are operatively coupled to an other component of the three-dimensional printing system and wherein the one or more operations comprise directing the other component. In some embodiments, directing the other component is for participation of the other component in three-dimensional printing. In some embodiments, the program instructions are inscribed in one or more non-transitory media, or in one or more data carriers. In some embodiments, the program instructions are included in one or more computer products. In some embodiments, the one or more operations are operations, wherein the one or more processors are processors, and wherein at least two of the operations are executed, or are directed, by different processors. In some embodiments, the one or more processors are processors, and wherein the one or more operations is operations, and wherein at least two of the operations are executed, or are directed, by the same processor of the one or more processors.

[0012] In another aspect, a method for generating a planar layer of powder material, the method comprising: providing any of the devices above; and performing one or more operations associated with the device comprising using the device to dispense the planar layer. In an example, a method for generating a planar layer of powder material, the method comprises: dispensing at least a first portion of powder material through an exit port of a dispenser for generating a first layer having a first exposed surface that is substantially planar according to a first central tendency of planarity, the first exposed surface having a second central tendency of thickness of the first layer, the dispenser comprises (I) the exit port and (II) a reservoir configured to accommodate powder material, the dispensing comprises inducing an increase of a flow rate of the powder material from the exit port of the dispenser towards a (e.g., planar) target surface at least in part by using an agitator that is operatively coupled to, or is part of, the dispenser; wherein: (A) the target surface includes one or more protrusions from the target surface, the one or more protrusions being of one or more three-dimensional objects, and wherein the second central tendency of the thickness of the first layer is smaller than a maximal height (e.g., vertical distance) of the one or more protrusions from the target surface, (B) the method further comprises removing a second portion of powder material from the first layer for generating a second layer of powder material having a second exposed surface that is substantially planar according to a third central tendency of planarity, the third central tendency of planarity being of the same type as the first central tendency of planarity, and wherein the third central tendency of planarity is smaller than the first central tendency of planarity of the first layer such that the third central tendency of planarity is indicative of a more planar surface than the first tendency of planarity, (C) the second layer has a thickness having a fourth central tendency of thickness of the same type as the second central tendency of thickness, wherein during use of the dispenser, a closest distance between the target surface and the dispenser is larger than (a) the second central tendency of thickness of the first layer and/or (b) the fourth central tendency of thickness of the second layer, (D) the agitator is separated from the dispenser, (E) the agitator is operatively coupled to a panel that is operatively coupled to, or that is part of, the dispenser, the panel being arranged with respect to the exit port of the dispenser, the method further comprises (c) restricting, by the panel and in the first operating state, a flow of the powder material through the exit port of the dispenser and (d) allowing, by the panel and in the second operating state, the flow of the powder material from the exit port of the dispenser towards the target surface, (F) a transducer of the agitator is disposed outside of a processing chamber enclosing the first layer, (G) further comprises controlling a dew point of an interior atmosphere of the processing chamber to be (III) above a level of humidity at or below which the powder material agglomerates, and (IV) below a level in which the powder material absorbs water (e) such that the powder material becomes reactive under conditions of a three- dimensional printing process utilizing the powder material and/or (f) such that the absorbed water on the powder material is sufficient to cause a measurable defect in a three-dimensional object printed from the powder material, or (H) any combination of (A)-(G).

[0013] In another aspect, a system for three-dimensional printing, the system comprising: any of the devices above configured to generate a planar layer of powder material; and an energy beam configured to irradiate the planar layer of the powder material to print at least a portion of at least one three-dimensional object at least in part by using three-dimensional printing. In some embodiments, the system further comprises a scanner configured to translate the energy beam along the target surface, wherein the device is operatively coupled to the scanner. In some embodiments, the system further comprises an energy source configured to generate the energy beam, wherein the device is operatively coupled to the energy source. In some embodiments, the system is configured to operatively couple to at least one controller configured to (i) operatively couple to the device and (ii) direct one or more operations associated with the device. In some embodiments, the system further comprises at least one controller that (i) is operatively coupled to the system and (ii) directs one or more operations associated with the system.

[0014] In another aspect, a system for effectuating the methods, operations of an apparatus, and/or operations inscribed by non-transitory computer readable program instructions (e.g., inscribed on a media/medium), disclosed herein.

[0015] In another aspect, a system for effectuating the methods, operations of an apparatus, operation of a device, and/or operations inscribed by non-transitory computer readable program instructions (e.g., inscribed on a media/medium), disclosed herein.

[0016] In another aspect, device(s) (e.g., apparatus) for effectuating the methods, operations of an apparatus, and/or operations inscribed by non-transitory computer readable program instructions (e.g., inscribed on a media/medium).

[0017] In other aspects, systems, apparatuses (e.g., controller(s)), and/or non-transitory computer-readable program instructions (e.g., software) that implement any of the methods disclosed herein. In some embodiments, the program instructions is inscribed on at least one medium (e.g., on a medium or on media).

[0018] In other aspects, methods, systems, apparatuses (e.g., controller(s)), and/or non- transitory computer-readable program instructions (e.g., software) that implement any of the devices disclosed herein and/or any operation of these devices. In some embodiments, the program instructions is inscribed on at least one medium (e.g., on a medium or on media). [0019] In another aspect, an apparatus (e.g., for printing one or more 3D objects) comprises at least one controller that is configured (e.g., programmed) to direct a mechanism used in a 3D printing methodology to implement (e.g., effectuate) any of the method and/or operations disclosed herein, wherein the controller(s) is operatively coupled with the mechanism. In some embodiments, the controller(s) implements any of the methods and/or operations disclosed herein. In some embodiments, the at least one controller comprises, or be operatively coupled with, a hierarchical control system. In some embodiments, the hierarchical control system comprises at least three, four, or five, control levels. In some embodiments, at least two operations are performed, or directed, by the same controller. In some embodiments, at least two operations are each performed, or directed, by a different controller.

[0020] In another aspect, an apparatus (e.g., for printing one or more 3D objects) comprises at least one controller that is configured (e.g., programmed) to implement (e.g., effectuate), or direct implementation of, the method, process, and/or operation disclosed herein. In some embodiments, the at least one controller implements any of the methods, processes, and/or operations disclosed herein.

[0021] In another aspect, non-transitory computer readable program instructions (e.g., for printing one or more 3D objects), when read by one or more processors, are configured to execute, or direct execution of, the method, process, and/or operation disclosed herein. In some embodiments, the at least one controller implements any of the methods, processes, and/or operations disclosed herein. In some embodiments, at least a portion of the one or more processors is part of a 3D printer, outside of the 3D printer, or in a location remote from the 3D printer (e.g., in the cloud).

[0022] In another aspect, a system for printing one or more 3D objects comprises an apparatus (e.g., used in a 3D printing methodology) and at least one controller that is configured (e.g., programmed) to direct operation of the apparatus, wherein the at least one controller is operatively coupled with the apparatus. In some embodiments, the apparatus includes any apparatus or device disclosed herein. In some embodiments, the at least one controller implements, or direct implementation of, any of the methods disclosed herein. In some embodiments, the at least one controller directs any apparatus (or component thereof) disclosed herein.

[0023] In some embodiments, at least two of operations (e.g., instructions) of the apparatus are directed by the same controller. In some embodiments, at least two of operations (e.g., instructions) of the apparatus are directed by different controllers.

[0024] In some embodiments, at least two of operations (e.g., instructions) are carried out by the same processor and/or by the same sub-computer software product. In some embodiments, at least two of operations (e.g., instructions) are carried out by different processors and/or by different sub-computer software products.

[0025] In another aspect, a computer software product, comprising a (e.g., non-transitory) computer-readable medium/media in which program instructions are stored, which instructions, when read by a computer, cause the computer to direct a mechanism used in the 3D printing process to implement (e.g., effectuate) any of the method disclosed herein, wherein the non- transitory computer-readable medium is operatively coupled with the mechanism. In some embodiments, the mechanism comprises an apparatus or an apparatus component.

[0026] In another aspect, a computer system comprising one or more computer processors and non-transitory computer-readable medium/media coupled thereto. In some embodiments, the non-transitory computer-readable medium/media comprises machine-executable code that, upon execution by the one or more computer processors, implements any of the methods and/or operations (e.g., as disclosed herein), and/or effectuates directions of the controller(s) (e.g., as disclosed herein).

[0027] In another aspect, a method for three-dimensional printing, the method comprises executing one or more operations associated with at least one configuration of the device(s) disclosed herein.

[0028] In another aspect, an apparatus for three-dimensional printing, the apparatus comprising at least one controller is configured (i) operatively couple with (e.g., to) the device, and (ii) direct executing one or more operations associated with at least one configuration of the device(s) disclosed herein.

[0029] In another aspect, at least one controller is associated with the methods, devices, and software disclosed herein. In some embodiments, the at least one controller comprise at least one connector configured to connect to a power source. In some embodiments, the at least one controller being configured to operatively couple with (e.g., to) a power source at least in part by (I) having a power socket and/or (II) being configured for wireless power transfer using inductive charging. In some embodiments, the at least one controller is included in, or comprises, a hierarchical control system. In some embodiments, the hierarchical control system comprises at least three hierarchical control levels. In some embodiments, the at least one controller is included in a control system configured to control a three-dimensional printer that prints the one or more three-dimensional objects. In some embodiments, the at least one controller is configured to control at least one other component of a 3D printing system. In some embodiments, the device disclosed herein is a component of a three-dimensional printing system, and wherein the at least one controller is configured to (i) operatively couple with (e.g., to) another component of the three-dimensional printing system and (ii) direct operation of the other component. In some embodiments, the at least one controller is configured to direct operation of the other component at least in part for participation of the other component in three-dimensional printing. In some embodiments, the at least one controller is operatively coupled with at least about 900 sensors, or 1000 sensors operatively couple with (e.g., to) the three-dimensional printer. In some embodiments, the at least one controller is configured to control a pressure in the three-dimensional printer to be above ambient pressure external to the three-dimensional printer. In some embodiments, the at least one controller is configured to control an internal atmosphere of the three-dimensional printer to be depleted of a reactive agent relative to its concentration in an ambient atmosphere external to the device, the reactive agent being configured to react with a starting material of the three-dimensional printing at least during the three-dimensional printing.

[0030] In another aspect, non-transitory computer readable program instructions for three- dimensional printing, the non-transitory computer readable program instructions, when read by one or more processors operatively couped to the device, cause the one or more processors to direct executing one or more operations associated with at least one configuration of the device(s) disclosed herein.

[0031] In some embodiments, the program instructions are of a computer product.

[0032] In another aspect, a system for three-dimensional printing, the system comprising: the any of the devices above; and an energy beam configured to irradiate powder material (e.g., a planar layer of powder material) to print at least a portion of at least one three-dimensional object at least in part by using three-dimensional printing. In some embodiments, the system further comprising a scanner configured to translate the energy beam along a target surface, wherein the device is operatively coupled with the scanner disposed in an optical system enclosure or a portion thereof (e.g., optical housing). In some embodiments, the system further comprises an energy source configured to generate the energy beam, wherein the device is operatively coupled with the energy source. In some embodiments, the energy source comprises a laser source or an electron beam source. In some embodiments, the system further comprises at least one controller that (i) is operatively coupled with the device and (ii) direct one or more operations associated with the device. In some embodiments, the system is configured to operatively couple with (e.g., to) at least one controller configured to (i) operatively couple with (e.g., to) the system and (ii) direct one or more operations associated with the system.

[0033] The various embodiments in any of the above aspects are combinable (e.g., within an aspect), as appropriate.

[0034] Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. INCORPORATION BY REFERENCE

[0035] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF DRAWINGS

[0036] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings or figures (also “Fig.” and “Figs.” Herein), of which:

[0037] Fig. 1 schematically illustrates a side view of a three-dimensional (3D) printing system and its components;

[0038] Fig. 2 schematically illustrates a side view of components in a 3D printing system;

[0039] Fig. 3 schematically illustrates a computer control system that is programmed or otherwise configured to facilitate the formation of one or more 3D objects;

[0040] Fig. 4 illustrates a path;

[0041] Fig. 5 illustrates various paths;

[0042] Fig. 6 schematically illustrates a cross sectional portion of a 3D object;

[0043] Fig. 7 shows various vertical cross sectional views of 3D objects;

[0044] Fig. 8 schematically illustrates a coordinate system;

[0045] Fig. 9 schematically illustrates various 3D objects;

[0046] Fig. 10 schematically illustrates a side view of a 3D printing system and its components, and a schematic representation of a vertical cross section of a layer of prep- transformed material as part of a material bed;

[0047] Fig. 11 schematically illustrates a side view of a 3D printing system and its components;

[0048] Fig. 12 shows a block diagram of a 3D printing system and its components;

[0049] Fig. 13 schematically illustrates a side view of 3D printer components;

[0050] Fig. 14 shows various schematic views of 3D printer components;

[0051] Fig. 15 shows various schematic views of 3D printer components;

[0052] Fig. 16 shows various schematic views of 3D printer components;

[0053] Fig. 17 shows various schematic views of 3D printer components;

[0054] Fig. 18 shows various schematic views of 3D printer components;

[0055] Fig. 19 shows various schematic views of 3D printer components;

[0056] Fig. 20 shows various schematic views of 3D printer components;

[0057] Fig. 21 shows various schematic views of 3D printer components;

[0058] Fig. 22 shows various schematic views of 3D printer components;

[0059] Fig. 23 shows various schematic views of 3D printer components; [0060] Fig. 24 shows various schematic views of 3D printer components;

[0061] Fig. 25 shows a schematic view of a 3D printer component;

[0062] Fig. 26 shows various schematic views of 3D printer components;

[0063] Fig. 27 shows various schematic views of 3D printer components;

[0064] Fig. 28 shows a schematic view of a 3D printer component;

[0065] Fig. 29 shows a schematic view of a 3D printer component;

[0066] Fig. 30 shows various schematic views of 3D printer components;

[0067] Fig. 31 is a flow diagram of an example process of a 3D printing system;

[0068] Fig. 32 shows a schematic view of a 3D printing system and its components;

[0069] Fig. 33 shows schematic views of a 3D printing system and its components;

[0070] Fig. 34 shows various schematic views of 3D printer components;

[0071] Fig. 35 shows various schematic views of 3D printer components; and

[0072] Fig. 36 shows various schematic views of a portion of a 3D printer component.

[0073] The figures and components therein may not be drawn to scale. Various components of the figures described herein may not be drawn to scale.

DETAILED DESCRIPTION

[0074] While various embodiments of the invention have been shown, and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein might be employed. The various embodiments disclosed herein are combinable, as appropriate.

[0075] Terms such as “a”, “an” and “the” are not intended to refer to only a singular entity but include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments in the present disclosure, but their usage does not delimit to the specific embodiments of the present disclosure. The term "includes" means includes but not limited to, the term "including" means including but not limited to, and the term "based on" means based at least in part on.

[0076] When ranges are mentioned, the ranges are meant to be inclusive, unless otherwise specified. For example, a range between value 1 and value 2 is meant to be inclusive and include value 1 and value 2. The inclusive range will span any value from about value 1 to about value 2. The term “adjacent” or “adjacent to,” as used herein, includes “next to,” “adjoining,” “in contact with,” and “in proximity to.” When ranges are mentioned (e.g., between, at least, at most, and the like) the endpoint(s) of the range is/are also claimed. For example, when the range is from Xto Y, the values of X and Y are also claimed. For example, when the range is at most Z, the value of Z is also claimed. For example, when the range is at least W, the value of W is also claimed. [0077] The conjunction “and/or” as used herein in “X and/or Y” - including in the specification and claims - is meant to include the options (i) X, (ii) Y, and (iii) X and Y, as applicable. The conjunction of “and/or” in the phrase “including X, Y, and/or Z” is meant to include any combination and any plurality thereof, as applicable. For example, it is meant to include the following: (1) a single X, (2) a single Y, (3) a single Z, (4) a single X and a single Y, (5) a single X and a single Z, (6) a single Y and a single Z, (7) a single X, a single Y, and a single Z, (8) a plurality of X, (9) a plurality of Y, (10) a plurality of Z, (11) a plurality of X and a single Y, (12) a plurality of X, a single Y and a single Z, (13) a plurality of X and a single Z, (14) a plurality of Y and a single X, (15) a plurality of Y, a single X, and a single Z, (16) a plurality of Y and a single Z, (17) a plurality of Z and a single X, (18) a plurality of Z, a single X, and a single Y (19) a plurality of Z and a single Y, (20) a plurality X and a plurality Y, (21) a plurality X and a plurality Z, (22) a plurality Y and a plurality Z, and (23) a plurality X, a plurality Y, and a plurality Z. The phrase “including X, Y, and/or Z” is meant to have the same meaning as the phrase “comprising X, Y, or Z.”

[0078] The term “operatively coupled” or “operatively connected” refers to a first mechanism that is coupled (or connected) to a second mechanism to allow the intended operation of the second and/or first mechanism. The coupling may comprise physical or non-physical coupling. The non-physical coupling may comprise signal induced coupling (e.g., wireless coupling). [0079] The phrase “is/are structured” or “is/are configured,” when modifying an article, refers to a structure of the article that is able to bring about the referred result.

[0080] Fundamental length scale (abbreviated herein as “FLS”) can be referred herein as to any suitable scale (e.g., dimension) of an object. For example, a FLS of an object may comprise a length, a width, a height, a diameter, a spherical equivalent diameter, or a diameter of a bounding sphere. In some cases, FLS may refer to an area, a volume, a shape, or a density.

[0081] A central tendency as understood herein comprises mean, median, or mode. The mean may comprise a geometric mean.

[0082] Performing a reversible first operation is understood herein to mean performing the first operation and being capable of performing the opposite of that first operation (e.g., which is a second operation). For example, when a controller directs reversibly opening a shutter, that shutter can also close, and the controller can optionally direct a closure of that shutter. For example, when a layer dispensing mechanism (e.g., recoater) reversibly translates in a first direction, that layer dispensing mechanism (e.g., recoater) can also translate in a second direction opposite to the first direction. For example, when a controller directs reversibly translating a recoater in a first direction, that recoater can translate in the first direction and can also translate in a second direction opposite to the first direction, e.g., when the controller directs the recoater to translate in the second direction.

[0083] Where suitable, one or more of the features shown in a figure comprising a 3D printer and/or components thereof can be combined with one or more of the various features of other 3D printers and/or components thereof described herein. A figure shown herein may not show certain features of a 3D printer and/or components thereof described herein. It should be understood that any such features can be incorporated within the 3D printer as requested and where suitable.

[0084] Any of the apparatuses and/or their components disclosed herein may be built by at least one material disclosed herein. The apparatuses and/or their components comprise a transparent or non-transparent (e.g., opaque) material. For example, the apparatuses and/or their components may comprise an organic or an inorganic material. For example, the apparatuses and/or their components may comprise an elemental metal, metal alloy, ceramic, or an allotrope of elemental carbon. For example, the enclosure, platform, recycling system, or any of their components may comprise an elemental metal, metal alloy, ceramic, or an allotrope of elemental carbon.

[0085] The present disclosure provides three-dimensional (3D) printing apparatuses, systems, software, and methods for forming a 3D object. For example, a 3D object may be formed at least in part by sequential addition of material or joining of starting material (e.g., pretransformed material or source material) to form a structure in a controlled manner (e.g., under manual or automated control).

[0086] Transformed material, as understood herein, is a material that underwent a physical change. The physical change can comprise a phase change. The physical change can comprise fusing (e.g., melting or sintering), connecting, or bonding (e.g., physical, or chemical bond). The physical change can be a phase transformation such as from a solid to a partially liquid, or to a liquid phase.

[0087] The 3D printing process may comprise printing one or more layers of hardened material in a building cycle, e.g., in a printing cycle. A building cycle (e.g., printing cycle), as understood herein, comprises printing the (e.g., hardened, or solid) material layers of a print job (e.g., all, or substantially all, the layers of a printing job), which may comprise printing one or more 3D objects above a platform (e.g., in a single material bed). The one or more 3D object(s) may or may not be physically anchored to the platform (e.g., a build platform) above which it/they are printed.

[0088] Pre-transformed material (also referred to herein as “starting material”), as understood herein, is a material before it has been transformed (e.g., once transformed) by an energy beam during an upcoming 3D printing process, e.g., it is a starting material for an upcoming 3D printing process. The pre-transformed material may be a material that was, or was not, transformed prior to its use in the upcoming 3D printing process. The pre-transformed material may be a material that was partially transformed prior to its use in the upcoming 3D printing process. The pre-transformed material may be a starting material for the upcoming 3D printing process. The pre-transformed material may be liquid, solid, or semi-solid (e.g., gel). The pretransformed material may be a particulate material. For example, the particulate material may be a powder material. The powder material may comprise solid particles of material(s). The particulate material may comprise vesicles (e.g., containing liquid or semi-solid material). The particulate material may comprise solid or semi-solid material particles. The pre-transformed material may be in the form of a powder, wires, sheets, or droplets. The pre-transformed material may be pulverous. The pre-transformed material may have been deposited during a 3D printer process prior to the upcoming 3D printing process. For example, in a first 3D printing process (having a first build cycle), powder material was used to form a 3D object. A remainder of the powder material of the first 3D printing process may become a pre-transformed material for an upcoming second 3D printing process (having a second build cycle). Thus, even though the remainder powder of the first 3D printing process may comprise transformed material (e.g., bits of sintered powder), it is still considered a pre-transformed material relative to the second 3D printing process. The remainder can be filtered and otherwise recycled for use as a pretransformed material in the second 3D printing process.

[0089] In some embodiments, in a 3D printing process, the deposited pre-transformed material may be fused, (e.g., sintered or melted), bound or otherwise connected to form at least a portion of the requested 3D object. Fusing, binding or otherwise connecting the material is collectively referred to herein as “transforming” the material. Fusing the material may refer to melting, smelting, or sintering a pre-transformed material.

[0090] In some embodiments, melting may comprise liquefying the material (i.e., transforming to a liquefied state). A liquefied state refers to a state in which at least a portion of a transformed material is in a liquid state. Melting may comprise liquidizing the material (i.e., transforming to a liquidus state). A liquidus state refers to a state in which an entire transformed material is in a liquid state. The apparatuses, methods, software, and/or systems provided herein are not limited to the generation of a single 3D object but may be utilized to generate one or more 3D objects simultaneously (e.g., in parallel) or separately (e.g., sequentially). The multiplicity of 3D object may be formed in one or more material beds (e.g., powder bed). In some embodiments, a plurality of 3D objects is formed in one material bed.

[0091] In some examples, 3D printing methodologies comprise extrusion, wire, granular, laminated, light polymerization, or powder bed and inkjet head 3D printing. Extrusion 3D printing can comprise robo-casting, fused deposition modeling (FDM) or fused filament fabrication (FFF). Wire 3D printing can comprise electron beam freeform fabrication (EBF3). Granular 3D printing can comprise direct metal laser sintering (DMLS), electron beam melting (EBM), selective laser melting (SLM), selective heat sintering (SHS), or selective laser sintering (SLS). Powder bed and inkjet head 3D printing can comprise plaster-based 3D printing (PP). Laminated 3D printing can comprise laminated object manufacturing (LOM). Light polymerized 3D printing can comprise stereo-lithography (SLA), digital light processing (DLP), or laminated object manufacturing (LOM). 3D printing methodologies can comprise Direct Material Deposition (DMD). The Direct Material Deposition may comprise, Laser Metal Deposition (LMD, also known as, Laser deposition welding). 3D printing methodologies can comprise powder feed, or wire deposition.

[0092] In some examples, 3D printing methodologies differ from methods traditionally used in semiconductor device fabrication (e.g., vapor deposition, etching, annealing, masking, or molecular beam epitaxy). In some instances, 3D printing may further comprise one or more printing methodologies that are traditionally used in semiconductor device fabrication. 3D printing methodologies can differ from vapor deposition methods such as chemical vapor deposition, physical vapor deposition, or electrochemical deposition. In some instances, 3D printing may further include vapor deposition methods.

[0093] In an aspect provided herein is a system for generating a 3D object comprising: an enclosure for accommodating at least one layer of pre-transformed material (e.g., powder); an energy (e.g., energy beam) capable of transforming the pre-transformed material to form a transformed material; and a controller that directs the energy to impinge on the exposed surface of the layer of pre-transformed material and translate along a path (e.g., as described herein). The transformed material may be capable of hardening to form at least a portion of a 3D object. The system may comprise an energy source generating the energy beam, an optical system, a control system, a layer dispensing mechanism such as a recoater, gas source(s), pump(s), nozzle(s), valve(s), sensor(s), display(s), chamber(s), processor(s) comprising or software (e.g., comprising computational schemes such as algorithm(s)) inscribed on a computer readable media/medium. The control system may be configured to control temperature, pressure, gas flow, optics, actuator(s), energy source(s), energy beam(s), and/or atmosphere(s). The chamber may comprise a platform including a base and a substrate. The base may be referred to herein as the “build plate” or “building platform.” The substrate may comprise an elevator piston. The system for generating at least one 3D object (e.g., in a printing cycle) and its components may be any 3D printing system, e.g., as disclosed herein. Examples of 3D printers, their components, and associated methods, software, systems, devices, and apparatuses, can be found in International Patent Application Serial No. PCT/US17/60035, filed November 3, 2017; and in International Patent Application Serial No. PCT/US22/16550, filed February 26, 2022; each of which is entirely incorporated herein by reference.

[0094] In some embodiments, the deposited pre-transformed material within the enclosure is a liquid material, semi-solid material (e.g., gel), or a solid material (e.g., powder). The deposited pre-transformed material within the enclosure can be in the form of a powder, wires, sheets, or droplets. The material (e.g., pre-transformed, transformed, and/or hardened) may comprise elemental metal, metal alloy, ceramics, or an allotrope of elemental carbon. The allotrope of elemental carbon may comprise amorphous carbon, graphite, graphene, diamond, or fullerene. The fullerene may be selected from the group consisting of a spherical, elliptical, linear, and tubular fullerene. The fullerene may comprise a buckyball, or a carbon nanotube. The ceramic material may comprise cement. The ceramic material may comprise alumina, zirconia, or carbide (e.g., silicon carbide, or tungsten carbide). The ceramic material may include high performance material (HPM). The ceramic material may include a nitride (e.g., boron nitride or aluminum nitride). The material may comprise sand, glass, or stone. In some embodiments, the material may comprise an organic material, for example, a polymer or a resin (e.g., 114 W resin). The organic material may comprise a hydrocarbon. The polymer may comprise styrene or nylon (e.g., nylon 11). The polymer may comprise a thermoplast. The organic material may comprise carbon and hydrogen atoms. The organic material may comprise carbon and oxygen atoms. The organic material may comprise carbon and nitrogen atoms. The organic material may comprise carbon and sulfur atoms. In some embodiments, the material may exclude an organic material. The material may comprise a solid or a liquid. In some embodiments, the material may comprise a silicon-based material, for example, silicon-based polymer or a resin. The material may comprise an organosilicon-based material. The material may comprise silicon and hydrogen atoms. The material may comprise silicon and carbon atoms. In some embodiments, the material may exclude a silicon-based material. The powder material may be coated by a coating (e.g., organic coating such as the organic material (e.g., plastic coating)). The material may be devoid of organic material. The liquid material may be compartmentalized into reactors, vesicles, or droplets. The compartmentalized material may be compartmentalized in one or more layers. The material may be a composite material comprising a secondary material. The secondary material can be a reinforcing material (e.g., a material that forms a fiber). The reinforcing material may comprise a carbon fiber, Kevlar®, Twaron®, ultra-high- molecular-weight polyethylene, or glass fiber. The material can comprise powder (e.g., granular material) and/or wires. The bound material can comprise chemical bonding. Transforming can comprise chemical bonding. Chemical bonding can comprise covalent bonding. The pretransformed material may be pulverous. The printed 3D object can be made of a single material (e.g., single material type) or multiple materials (e.g., multiple material types). Sometimes one portion of the 3D object and/or of the material bed may comprise one material, and another portion may comprise a second material different from the first material. The material may be a single material type (e.g., a single alloy or a single elemental metal). The material may comprise one or more material types. For example, the material may comprise two alloys, an alloy and an elemental metal, an alloy and a ceramic, or an alloy and an elemental carbon. The material may comprise an alloy and alloying elements (e.g., for inoculation). The material may comprise blends of material types. The material may comprise blends with elemental metal or with metal alloy. The material may comprise blends excluding (e.g., without) elemental metal or including (e.g., with) metal alloy. The material may comprise a stainless steel. The material may comprise a titanium alloy, aluminum alloy, and/or nickel alloy.

[0095] In some cases, a layer within the 3D object comprises a single type of material. In some examples, a layer of the 3D object may comprise a single elemental metal type, or a single alloy type. In some examples, a layer within the 3D object may comprise several types of material (e.g., an elemental metal and an alloy, an alloy and a ceramic, an alloy and an elemental carbon). In certain embodiments, each type of material comprises only a single member of that type. For example: a single member of elemental metal (e.g., iron), a single member of metal alloy (e.g., stainless steel), a single member of ceramic material (e.g., silicon carbide or tungsten carbide), or a single member of elemental carbon (e.g., graphite). In some cases, a layer of the 3D object comprises more than one type of material. In some cases, a layer of the 3D object comprises more than member of a type of material.

[0096] In some examples, the material bed, and/or 3D printing system (or any component thereof such as a build platform) may comprise any material disclosed herein. The material may comprise a material type which constituents (e.g., atoms) readily lose their outer shell electrons, resulting in a free-flowing cloud of electrons within their otherwise solid arrangement. The material bed may comprise a particulate material (e.g., powder). In some examples the material (e.g., powder, and/or 3D printer component) may comprise a material characterized in having high electrical conductivity, low electrical resistivity, high thermal conductivity, or high density. The high electrical conductivity can be at least about 1*105 Siemens per meter (S/m), 5*105 S/m, 1*106 S/m, 5*106 S/m, 1*107 S/m, 5*107 S/m, or 1*108 S/m. The symbol “*” designates the mathematical operation “times.” The high electrical conductivity can be between any of the afore-mentioned electrical conductivity values (e.g., from about 1*105 S/m to about 1*108 S/m). The thermal conductivity, electrical resistivity, electrical conductivity, and/or density can be measured at ambient temperature (e.g., at R.T., or 20 °C). The low electrical resistivity may be at most about 1*10-5 ohm times meter (Q*m), 5*10-6 Q*m, 1*10-6 Q*m, 5*10-7 Q*m, 1*10-7 D*m, 5*10-8 or 1*10-8 D*m. The low electrical resistivity can be between any of the aforementioned values (e.g., from about 1X10-5 Q*m to about 1X10-8 Q*m). The high thermal conductivity may be at least about 10 Watts per meter times Kelvin (W/mK), 15 W/mK, 20 W/mK, 35 W/mK, 50 W/mK, 100 W/mK, 150 W/mK, 200 W/mK, 205 W/mK, 300 W/mK, 350 W/mK, 400 W/mK, 450 W/mK, 500 W/mK, 550 W/mK, 600 W/mK, 700 W/mK, 800 W/mK, 900 W/mK, or 1000 W/mK. The high thermal conductivity can be between any of the aforementioned thermal conductivity values (e.g., from about 20 W/mK to about 1000 W/mK). The high density may be at least about 1.5 grams per cubic centimeter (g/cm3), 1 .7 g/cm3, 2 g/cm3, 2.5 g/cm3, 2.7 g/cm3, 3 g/cm3, 4 g/cm3, 5 g/cm3, 6 g/cm3, 7 g/cm3, 8 g/cm3, 9 g/cm3, 10 g/cm3, 11 g/cm3, 12 g/cm3, 13 g/cm3, 14 g/cm3, 15 g/cm3, 16 g/cm3, 17 g/cm3, 18 g/cm3, 19 g/cm3, 20 g/cm3, or 25 g/cm3. The high density can be any value between the afore mentioned values (e.g., from about 1 g/cm3 to about 25 g/cm3).

[0097] In some embodiments, the elemental metal is an alkali metal, an alkaline earth metal, a transition metal, a rare-earth element metal, a precious metal, or another metal. The elemental metal may comprise Titanium, Copper, Platinum, Gold, or Silver.

[0098] In some embodiments, the metal alloy comprises iron-based alloy, nickel-based alloy, cobalt-based alloy, chrome based alloy, cobalt chrome based alloy, titanium based alloy, magnesium based alloy, or copper based alloy. The alloy may comprise an oxidation or corrosion resistant alloy. The alloy may comprise a super alloy (e.g., Inconel). The alloy may comprise an alloy used for aerospace applications, automotive application, surgical application, or implant applications. The metal may include a metal used for aerospace applications, automotive application, surgical application, or implant applications.

[0099] In some embodiments, the metal alloys are Refractory Alloys. The refractory metals and alloys may be used for heat coils, heat exchangers, furnace components, or welding electrodes. The Refractory Alloys may comprise a high melting points, low coefficient of expansion, mechanically strong, low vapor pressure at elevated temperatures, high thermal conductivity, or high electrical conductivity.

[0100] In some embodiments, the material (e.g., alloy or elemental) comprises a material used for applications in industries comprising aerospace (e.g., aerospace super alloys), jet engine, missile, automotive, marine, locomotive, satellite, defense, oil & gas, energy generation, semiconductor, fashion, construction, agriculture, printing, or medical. The material may comprise an alloy used for products comprising, devices, medical devices (human & veterinary), machinery, cell phones, semiconductor equipment, generators, engines, pistons, electronics (e.g., circuits), electronic equipment, agriculture equipment, motor, gear, transmission, communication equipment, computing equipment (e.g., laptop, cell phone, i-pad), air conditioning, generators, furniture, musical equipment, art, jewelry, cooking equipment, or sport gear. The material may comprise an alloy used for products for human or veterinary applications comprising implants, or prosthetics. The metal alloy may comprise an alloy used for applications in the fields comprising human or veterinary surgery, implants (e.g., dental), or prosthetics.

[0101] In some embodiments, the alloy includes a high-performance alloy. The alloy may include an alloy exhibiting at least one of excellent mechanical strength, resistance to thermal creep deformation, good surface stability, resistance to corrosion, and resistance to oxidation. The alloy may include a face-centered cubic austenitic crystal structure. The alloy can be a single crystal alloy. Examples of materials, 3D printers, and associated methods, software, systems, devices, materials (e.g., alloys), and apparatuses, can be found in International Patent Application Serial No. PCT/US17/60035, filed November s, 2017; and in International Patent Application Serial No. PCT/US22/16550, filed February 26, 2022; each of which is entirely incorporated herein by reference.

[0102] In some embodiments, the elemental carbon comprises graphite, Graphene, diamond, amorphous carbon, carbon fiber, carbon nanotube, or fullerene.

[0103] In some embodiments, the material comprises powder material (also referred to herein as a “pulverous material”). The powder material may comprise a solid comprising fine particles. The powder may be a granular material. The powder can be composed of individual particles. At least some of the particles can be spherical, oval, prismatic, cubic, or irregularly shaped. At least some of the particles can have a fundamental length scale (e.g., diameter, spherical equivalent diameter, length, width, depth, or diameter of a bounding sphere). The central tendency of the fundamental length scale (abbreviated herein as “FLS”) of the particles can be from about 5 micrometers (pm) to about 100 pm, from about 10 pm to about 70 pm, or from about 50 pm to about 100 pm. The particles can have central tendency of the FLS of at most about 75 pm, 65 pm, 50 pm, 30 pm, 25 pm or less. The particles can have a central tendency of the FLS of at least 10 pm, 25 pm, 30 pm, 50 pm, 70 pm, or more. A central tendency of the distribution of an FLS of the particles (e.g., range of an FLS of the particles between largest particles and smallest particles) can be about at least about 5 pm, 10 pm, 20 pm, 30 pm, 40 pm, 53 pm, 60 pm, or 75 pm. The particles can have a central tendency of the FLS of at most about 65 pm. In some cases, the powder particles may have central tendency of the FLS between any of the aforementioned FLSs.

[0104] In some embodiments, the powder comprises a particle mixture, which particle comprises a shape. The powder can be composed of a homogenously shaped particle mixture such that all the particles have substantially the same shape and FLS magnitude within at most about 1%, 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, or 40% distribution of FLS.

[0105] Fig. 1 shows an example of a 3D printing system 100 having a processing chamber 107 coupled to a build module 123. The build module comprises an elevator having an elevation mechanism 105 (e.g., comprising a shaft) that vertically translate a substrate (e.g., piston) 109 along arrow 112. The base 102 is disposed on substrate (e.g., piston) 109. Material bed 104 is disposed above base 102 (e.g., also referred herein as “building platform”, or “build plate”). Energy source (e.g., laser source) 121 generates energy beam 101 that traverses through an optical system 120 (e.g., comprising a scanner) and an optical window 115 into processing chamber 107 enclosing interior space 126 that can include an atmosphere. The processing chamber comprises a layer dispensing mechanism 122 that includes a dispenser 116 and a remover 118. Processing chamber 107 can include an optional temperature adjustment device (e.g., cooling plate), not shown. Seal 103 encircles the substrate and/or base, e.g., to deter (e.g., prevent) migration of material of the material bed from reaching the elevator mechanism 105 (e.g., shaft). Energy beam 101 impinges upon an exposed surface 119 of material bed 104, to form at least a portion of a 3D object 106.

[0106] In some examples, during at least a portion of the 3D printing process, the atmospheres of the build module and processing chamber may be separate. The build module may be mobile or stationary. The build module may comprise an elevator. The elevator may be connected to a platform. The elevator may be reversibly connected to at least a portion of the platform. The elevator may be irreversibly connected to the substrate (e.g., the piston). The build plate and/or substrate may be separated from one or more walls (e.g., side walls) of the build module by a seal (e.g., Fig. 1 , 103). The seal may be permeable to at least one gas, and impermeable to the pre-transformed (e.g., and to the transformed) material. The seal may not allow a solid material (e.g., a pre-transformed material and/or a transformed material) to pass through.

[0107] In some embodiments, the pre-transformed material (e.g., starting material for the 3D printing) is deposited in an enclosure. Fig. 1 shows an example of a build module container 123 (also referred to herein as a build module). The build module container can contain the pretransformed material (e.g., without spillage; such as in a material bed Fig. 1 , material bed 104). Material may be placed in or inserted to the container. The material may be deposited in, pushed to, sucked into, or lifted to a container. The material may be layered (e.g., spread) in the enclosure such as by using a layer dispensing mechanism 122. The build module container may be configured to enclosure a substrate (e.g., Fig. 1 , 109 such as an elevator piston). The substrate may be situated adjacent to the bottom of the build module container (e.g., Fig. 1 , 111). Bottom may be relative to the gravitational field along gravitational vector 199 pointing towards gravitational center G, or relative to the position of the footprint of the energy beam (e.g., Fig. 1 , energy beam 101) on the layer of pre-transformed material as part of a material bed such as 104. The footprint of the energy beam may follow a Gaussian bell shape. In some embodiments, the footprint of the energy beam does not follow a Gaussian bell shape. The build module container may comprise a platform comprising a base (e.g., Fig. 1 , build plate 102). The platform may comprise a substrate or a base. The base may reside adjacent to the substrate. For example, the base may (e.g., reversibly) connect to the substrate. The pre-transformed material may be layer-wise deposited adjacent to a side of the build module container, e.g., above and/or on the bottom of the build module container. The pre-transformed material may be layered adjacent to the substrate and/or adjacent to the base. Adjacent to may be above. Adjacent to may be directly above, or directly on. The substrate may have one or more seals that enclose the material in a selected area within the build module container (e.g., Fig. 1 , seals 103). The one or more seals may be flexible or non-flexible. The one or more seals may comprise a polymer or a resin. The build module container may comprise the base. The base may be situated within the build module container. The build module container may comprise the platform, which may be situated within the build module container. The enclosure, processing chamber, and/or building module container may comprise (I) a window (e.g., an optical window and/or a viewing window) or (II) an optical system (e.g., Fig. 1 , 120). An example of an optical window can be seen in Fig. 1 , optical window 115. The optical window may allow the energy beam to pass through without (e.g., substantial) energetic loss. During the 3D printing, a ventilator and/or gas flow may prevent debris (e.g., spatter) from accumulating on the surface of the optical window that is disposed within the enclosure (e.g., within the processing chamber). A portion of the enclosure that is occupied by the energy beam (e.g., during the 3D printing) can define a processing cone (e.g., a truncated processing cone). During the 3D printing may comprise during the entire 3D printing. The processing cone can be the space that is occupied by a non-reflected energy beam during the (e.g., entire) 3D printing. The processing cone can be the space that is occupied by an energy beam that is directed towards the material bed during the (e.g., entire) 3D printing. During the 3D printing may comprise during printing of a layer of hardened material.

[0108] In some embodiments, the 3D printer comprises a gas flow mechanism. The gas flow mechanism may be in fluidic contact with one or more enclosures of the 3D printer. For example, the gas flow mechanism may be in fluidic contact with (i) a processing chamber, (ii) a build module, (iii) an optical enclosure, or (iv) any combination thereof. The gas flow mechanism may be in fluidic contact with a processing chamber and/or a build module. The gas flow mechanism may be in fluid communication with the optical enclosure. At times, a gas flow assembly may be in fluid communication with the optical enclosure. The gas flow assembly may be configured to flow gas into and out of the optical enclosure. The gas flow assembly may be separate from the gas flow mechanism. For example, the gas flow mechanism and the gas flow assembly may be isolated (e.g., fluidically separate) from each other. The gas flow mechanism may be configured to flow gas into and out of the processing chamber.

[0109] In some embodiments, the 3D printer comprises a layer dispensing mechanism (e.g., Fig. 1 , 122). The pre-transformed material may be deposited in the enclosure by a layer dispensing mechanism (also referred to herein as a “layer dispenser,” or “layer forming apparatus,”). In some embodiments, the layer dispensing mechanism includes one or more material dispensers (e.g, Fig. 1 , material dispenser 116), and/or at least one material removal mechanism (also referred to herein as material “remover” or “material remover”) (e.g., Fig. 1 , removers 118) to form a layer of pre-transformed material (e.g., starting material) within the enclosure. The deposited starting material may be leveled by a material leveling mechanism (e.g., leveler) in a leveling operation. The leveling operation may comprise using a material removal mechanism that does not contact the exposed surface of the material bed. The material (e.g., powder) dispensing mechanism may comprise one or more dispensers. The material dispensing mechanism may comprise at least one material (e.g., bulk) reservoir. The material may be deposited by a layer dispensing mechanism (e.g., recoater). The layer dispensing mechanism may level the dispensed material without contacting the material bed (e.g., the top surface of the powder bed). The layer dispensing mechanism and energy beam can translate and form the 3D object adjacent to the platform, in a 3D printing cycle during which the platform gradually lowers its vertical position to facilitate layer-wise formation of the 3D object. The layer dispensing mechanism and energy beam can translate and form the 3D object within the material bed (e.g., as described herein), while the platform gradually lowers its vertical position to facilitate layer-wise formation of the 3D object. The layer dispensing mechanism can be used to form at least a portion of the material bed. The layer dispensing mechanism can dispense material, remove material, and/or otherwise shape the material bed, e.g., shape an exposed surface of a layer of material of the material bed. The material can comprise a pre-transformed material or a debris. Shaping the material bed may comprise altering a shape of the exposed surface of the material bed, e.g., planarizing the exposed surface of the material bed. The layer dispensing mechanism can be in a layer forming mode when dispensing the material and/or shaping the material bed. The layer dispensing mechanism can be in a parked mode when the layer dispensing mechanism is in an idle position such as a parked position. The material dispensing mechanism (e.g. the dispenser) can comprise a reservoir configured to retain a volume of pre-transformed material. The volume of pre-transformed material may be equivalent to about the volume of pre-transformed material sufficient for at least one or more dispensed layers above the platform. For example, the volume of pre-transformed material may be equivalent to about the volume of starting material sufficient for at least an integer number of dispensed layers above the platform. For example, the volume of pre-transformed material retained within the reservoir can be at least about 2 cubic centimeters (cc), 4cc, 5cc, 10cc, 15cc, 20cc, 25 cc, 50 cc, 75 cc, 100 cc, 150 cc, 200 cc, 250 cc, 350 cc, 500 cc, 750 cc, 1000 cc, 1250 cc, 1500 cc, 2000 cc, or 2500 cc. The material dispensing mechanism can comprise a reservoir configured to retain a volume of pre-transformed material can be between any of the aforementioned amounts, for example, from about 2 cc to about 1200 cc, from about 2cc to about 50cc, from about 25 cc to about 1000 cc, or from about 20 cc to about 1500 cc. The material dispensing mechanism can dispense material at a dispensing rate (e.g., flow rate from the material dispensing mechanism) of at least 0.2 cubic centimeters per second (cm³/sec) or (cc/sec), 0.4 cm³/sec, 0.5 cm³/sec, 1 cm³/sec, or 2 cm³/sec, 2 cc/sec, 2.5 cc/sec, 3.5 cc/sec, 5 cc/sec, 10 cc/sec, 30 cc/sec, 50 cc/sec, 75 cc/sec, 90 cc/sec, 100 cc/sec, 110 cc/sec, 125 cc/sec, or 150 cc/sec. The dispensing rate can be between any of the afore-mentioned dispensing rates (e.g., from about 2 cc/sec to about 150 cc/sec, from about 2.5 cc/sec to about 100 cc/sec, from about 3.5 cc/sec to about 125 cc/sec, or from about 2.5 cc/sec to about 90 cc/sec).

[0110] At times, the layer dispensing mechanism (e.g., recoater) may dispense at least a portion of a layer of pre-transformed material. The dispensed (e.g., portion of a) layer of pretransformed material may comprise an exposed surface that is (e.g., substantially) planar. The planar exposed surface may be (e.g., substantially) horizontal, flat, smooth, and/or unvaried. The planar exposed surface may have a surface roughness, e.g., quantified by the deviations in the direction of the normal vector of a real surface from its ideal form. The surface roughness may be expressed using roughness parameter(s) such as the arithmetic average of profile height deviations from the mean line - denoted as R_a, maximum peak to valley height of the profile, within a single sampling length - denoted as R_z., or its average value over assessment length - denoted as R_z, or their area analogues, e.g., the R_a area analogue is a difference in height of each point compared to the arithmetical mean of the surface designated as S_a„ The surface roughness may be referred to herein as planarity of the surface. A central tendency of planarity may be referred to an average, mean, or median of the planarity of that surface, or of a roughness of that surface. For example, the central tendency of planarity of a surface may be expressed as the R_a value of the surface. Fig. 10 shows an example of a vertical cross section of layer 1050 having exposed surface 1051 , which layer 1050 is disposed in relation to gravitational vector 1099 directed towards gravitational center G. The layer has a central tendency of height (e.g., thickness) 1052 with the smallest height being h2 and the largest height being hi . In the schematic example shown in Fig. 10, the maximal roughness is A2 while the minimal roughness is A1 , and exposed surface 1051 of the layer has a central tendency of planarity of A3 that can be referred to as the central tendency of the roughness of exposed surface 1051. A substantially planar exposed surface of the material bed may comprise a substantially uniform pre-transformed material (e.g., powder) height of the exposed surface. The layer dispensing mechanism can provide a layer of material having a height uniformity (e.g., powder uniformity height or thickness) across the exposed layer of the material bed such that portions of the bed that are separated from one another by at least about 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, or 10 mm, have a height (e.g. a thickness) deviation of at most about 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4 mm, 3 mm, 2 mm, 1 mm, 500 pm, 400 pm, 300 pm, 200 pm, 100 pm, 90 pm, 80 pm, 70 pm, 60 pm, 50 pm, 40 pm, 30 pm, 20 pm, or 10 pm. The layer dispensing mechanism can provide layer height uniformity across the exposed layer of the material bed such that portions of the bed that are separated from one another by any value between the afore-mentioned height deviation values (e.g., from about 1 mm to about 10 mm) have a height deviation value of from about 10mm to about 10 pm. The layer dispensing mechanism can provide a (e.g., substantially) uniform height (e.g., powder uniformity height such as Fig. 30, 3066) across the exposed surface of the material bed, such a height (e.g., thickness) variation of the layer may be at most about 60%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, or less from a central tendency of the layer height, e.g., from an average, mean, or median of the layer height. The layer dispensing mechanism may dispense a layer of starting material having an exposed surface that has a central tendency of planarity (e.g., an Ra) value (e.g., a deviation from a horizontal plane) of at most about 150 pm, 130 pm, 100 pm, 70 pm, 50 pm, 40 pm, 30 pm, 20 pm, 10 pm, 5 pm, or less. The layer dispensing mechanism may dispense a layer of starting material having an exposed surface that has a central tendency of planarity (e.g., an Ra) value between any of the afore-mentioned values (e.g., from about 5 pm to about 150 pm, from about 5 pm to about 50 pm, from about 30 pm to about 100 pm, or from about 100 pm to about 150 pm). The layer dispensing mechanism can dispense a layer having a central tendency of layer thickness (e.g., layer height) of at least about 10 microns (pm), 20 pmm 30 pm, 40 pm, 50 pm, 100 pm, 150 pm, 200 pm, 250 pm, 300 pm, 350 pm, 400 pm, 450 pm, 500 pm, or more. The central tendency of layer thickness (e.g., layer height) of material dispensed in a layer of material can be between any of the afore-mentioned amounts (e.g., from about 10 pm to about 500 pm, from about 100 pm to about 500 pm, from about 10 pm to about 100 pm, from about 10 pm to about 500 pm). A central tendency may comprise mean, median, or mode. The mean may comprise a geometric mean. The time taken to dispense a layer of material can be at least about 0.1 seconds (sec), 0.2 sec, 0.3 sec, 0.5 sec, 1 sec, 2 sec, 3 sec, 4 sec, 5 sec, 8 sec, 9 sec, 10 sec, 15 sec, or 20 sec. The time taken to dispense a layer of material having an FLS (e.g., height or thickness) of any of the aforementioned values can be between any of the aforementioned times (e.g., from about 0.1 seconds to about 20 seconds, from about 0.2 seconds to about 1 second, from about 3 seconds to about 5 seconds, from about 0.5 seconds to about 20 seconds). The speed of movement of the layer dispensing mechanism during operation, e.g., during dispense of material onto a target surface, can range from about 25 millimeters/second (mm/sec) to about 1200 mm/sec. The speed of movement of the layer dispensing mechanism during operation can be at least about 25 mm/sec, 35 mm/sec, 50 mm/sec, 200 mm/sec, 500 mm/sec, 800 mm/sec, 1000 mm/sec, 1200 mm/sec or more. The speed of movement of the layer dispensing mechanism during operation can be between any of the afore-mentioned speeds (e.g., from about 25 mm/sec to about 500 mm/sec, from about 50 mm/sec to about 1000 mm/sec, or from about 35 mm/sec to about 1200 mm/sec). The layer dispensing mechanism may include any layer dispensing mechanism and/or material (e.g., powder) dispenser used in 3D printing such as. Examples of 3D printing systems, apparatuses, devices, and components (e.g., layer dispensing mechanisms), controllers, software, and 3D printing processes can be found in International Patent Application Serial No. PCT/US17/60035, filed November s, 2017; in International Patent Application Serial No. PCT/US22/16550, filed February 26, 2022; and in International Patent Application Serial No. PCT/US17/39422 filed on June 27, 2017, each of which is entirely incorporated herein by reference.

[0111] In some embodiments, the layer dispensing mechanism (e.g., layer dispenser) includes a material dispensing mechanism (e.g., a material dispenser) and a material removing mechanism (e.g., a material remover). The layer dispensing mechanism may be devoid of a leveler, e.g., devoid of a leveling knife. The dispenser may dispense a first layer having a first central tendency of planarity (e.g., a first Rvalue) and a second central tendency of layer thickness. The remover may remove a portion of the material from the first layer resulting in a second layer having a third central tendency of planarity (e.g., a second R_a value) and a fourth central tendency of layer thickness. The fourth central tendency of layer thickness of the second layer may be smaller (e.g., thinner) than the second central tendency of layer thickness of the first layer, e.g., the second layer is thinner than the first layer. The third central tendency of planarity of the second layer may be smaller than the first central tendency of planarity of the first layer, e.g., the second layer is more planar than the first layer. For example, the second R_a value of the second layer may be smaller than the first R_a value of the first layer, e.g., the second layer is less rough than the first layer. At times, a first a central tendency of planarity (e.g., first Rvalue) of an exposed surface of the material bed after depositing the first layer, is larger than a third a central tendency of planarity (e.g., second R_avalue) of an exposed surface of the material bed after removal of a portion of the material from the first layer to form the second layer. The central tendency of planarity may comprise a central tendency of a standard deviation, root-mean-square (RMS) roughness, peak-to-valley height, or the like, of the layer. For example, a third central tendency of planarity (e.g., second fi_avalue, or second Rz value) of an exposed surface of the material bed after removal of a portion of the material from the first layer to form the second layer is at most about 20%, 30%, 40%, 50%, 60%, or 70% of the first central tendency of planarity (e.g., first ff_avalue, or first R_z value respectively) of the exposed surface of the material bed after depositing the first layer. For example, a third central tendency of planarity of an exposed surface of the material bed after removal of a portion of the material from the first layer to form the second layer, is smaller than a difference between (i) a fourth central tendency of the second thickness of the second layer and (ii) a second central tendency of first thickness of the first layer. For example, a third central tendency of planarity of an exposed surface of the material bed after removal of a portion of the material from the first layer to form the second layer is disclosed above for the layer of starting material dispensed by the layer dispensing mechanism. In some embodiments, a first layer dispensing mechanism includes a leveler, a dispenser devoid of an agitating component, and a remover. In some embodiments, a second layer dispensing mechanism includes a dispenser comprising an agitating component, the second layer dispenser being devoid of a remover. The agitating component may be a panel configured to transmit the agitations such as a panel of which at least a portion acts as a sonic (e.g., ultrasonic) wave guide. A first time it takes to dispense a planar layer of material utilized for 3D printing using the first layer dispenser may be slower as compared to a second time it takes to dispense the planar layer of using the second layer dispenser. The slower time may be slower by at least about 5 times (*), 2.5*, 2*, 1.5*, 1 .25*, 1.2* or 1.1*, with the symbol “*” designating the mathematical operation “times”. In an example, it takes about 10 seconds to dispense a planar layer of material (e.g., powder) utilized for 3D printing (of 50 micrometer height) using the first layer dispenser, and it takes about 8 seconds to dispense the planar layer of the same characteristics (e.g., height and powder) using the second layer dispenser.

[0112] In some embodiments, the layer dispensing mechanism includes a material dispensing mechanism (e.g., a dispenser) and a material remover (e.g., a remover). A first volume of pretransformed (e.g., starting) material may be deposited in the enclosure by the material dispensing mechanism and a second volume of pre-transformed material may be removed from the enclosure by the material remover. For example, a second volume of removed material by the remover is at least about 45%, 50%, 75%, 80%, 90%, 95%, 97%, or 99% of the dispensed first volume of pre-transformed material. For example, a difference (e.g., A = L₂ - ^i) between a fourth central tendency of thickness of the second layer (L₂) and a second central tendency of thickness of the first layer (L can be from about 10 microns (pm) to about 800 pm. The difference between a fourth central tendency of thickness of the second layer (L₂) and a second central tendency of thickness of the first layer (LJ can be at most about 800 pm, 750 pm, 500 pm, 450 pm, 250 pm, 150 pm, 100 pm, 50 pm, 10 pm, or less. Examples of 3D printing systems, apparatuses, devices, and components (e.g., material dispensing mechanisms and material removal mechanisms), controllers, software, and 3D printing processes can be found in Patent Application serial number PCT/US15/36802 filed on June 19, 2015, titled “APPARATUSES, SYSTEMS AND METHODS FOR THREE-DIMENSIONAL PRINTING”; in Provisional Patent Application serial number 62/317,070 filed April 1 , 2016, titled “APPARATUSES, SYSTEMS AND METHODS FOR EFFICIENT THREE-DIMENSIONAL PRINTING”; in Patent Application serial number PCT/US 16/66000 filed on December 9, 2016, titled “SKILLFUL THREE- DIMENSIONAL PRINTING”; or in Provisional Patent Application serial number 62/265,817, filed December 10, 2015, titled “APPARATUSES, SYSTEMS AND METHODS FOR EFFICIENT THREE-DIMENSIONAL PRINTING”; each of which is incorporated herein in its entirety.

[0113] In some embodiments, the 3D object(s) are printed from a material bed. The FLS (e.g., width, depth, and/or height) of the material bed can be at least about 50 millimeters (mm), 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 200 mm, 250 mm, 280 mm, 400 mm, 500 mm, 600mm, 800 mm, 900 mm, 1 meter (m), 2 m or 5 m. The FLS (e.g., width, depth, and/or height) of the material bed can be at most about 50 millimeters (mm), 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 200 mm, 250 mm, 280 mm, 400 mm, 500 mm, 600mm, 800 mm, 900 mm, 1 meter (m), 2 m, or 5 m. The FLS of the material bed can be between any of the afore-mentioned values (e.g., from about 50 mm to about 5m, from about 250 mm to about 500 mm, from about 280 mm to about 1m, or from about 500mm to about 5m). In some embodiments, the FLS of the material bed is in the direction of the gas flow. The layer dispensing mechanism may include components comprising a material dispensing mechanism, material leveling mechanism, material removal mechanism, or any combination or permutation thereof.

[0114] In some embodiments, the layer dispensing mechanism may reside within an ancillary chamber. Examples of 3D printers and their components (e.g., ancillary chamber), associated methods, software, apparatuses, systems, and devices, may be any of the ones described in International Patent Application serial number PCT/US17/57340, filed October 19, 2017, titled “OPERATION OF THREE-DIMENSIONAL PRINTER COMPONENTS”, which is entirely incorporated herein by reference in its entirety. The layer dispenser may be physically secluded from the processing chamber when residing in the ancillary chamber. The ancillary chamber may be connected (e.g., reversibly) to the processing chamber. The ancillary chamber may be connected (e.g., reversibly) to the build module. The ancillary chamber may convey the layer dispensing mechanism adjacent to a platform (e.g., that is disposed within the build module). The layer dispensing mechanism may be retracted into the ancillary chamber (e.g., when the layer dispensing mechanism does not perform dispensing).

[0115] In some embodiments, the 3D printer comprises a base. The base (also herein, “printing platform” or “building platform”) may be disposed in the enclosure (e.g., in the build module and/or processing chamber). A platform may comprise the base. The platform may be configured to support a material bed. The platform may be configured to support one or more layers of pre-transformed material (e.g., as part of the material bed). The platform may be configured to support at least a portion of the 3D object (e.g., during forming of the 3D object). The platform may comprise a substrate or a base. The substrate and/or the base may be removable or non-removable (e.g., from the 3D printing system and/or relative to each other). The platform (e.g., substrate and/or base) may be fastened to the build module container (e.g., build module) and/or to each other. The platform (or any of its components) may be transportable. The transportation of the platform may be controlled and/or regulated by at least one controller (e.g., by a control system). The platform may be transportable horizontally, vertically, or at an angle (e.g., planar or compound). The control system may be any control system disclosed herein, e.g., a control system of the 3D printer such as the one controlling the energy beam.

[0116] In some examples, the 3D printing system requires operation of maximum a single standard daily work shift. The 3D printing system may require operation by a human operator working at most of about 8 hours (h), 7h, 6h, 5h, 4h, 3h, 2h, 1 h, or 0.5h a day. The 3D printing system may require operation by a human operator working between any of the aforementioned time frames (e.g., from about 8h to about 0.5h, from about 8h to about 4h, from about 6h to about 3h, from about 3h to about 0.5h, or from about 2h to about 0.5h a day).

[0117] In some embodiments, the enclosure and/or processing chamber of the 3D printing system may be opened to the ambient environment sparingly. In some embodiments, the enclosure and/or processing chamber of the 3D printing system may be opened by an operator (e.g., human) sparingly. Sparing opening may be at most once in at most every 1 , 2, 3, 4, or 5 weeks. The weeks may comprise weeks of standard operation of the 3D printer. In some embodiments, the 3D printer has a capacity of 1 , 2, 3, 4, or 5 full prints in terms of pretransformed material (e.g., starting material such as powder) reservoir capacity. The 3D printer may have the capacity to print a plurality of 3D objects in parallel, e.g., in one material bed. For example, the 3D printer may be able to print at least 2, 3, 4, 5, 6, 7, 8, 9, or 103D objects in parallel.

[0118] Ambient refers to a condition to which people are generally accustomed. For example, ambient pressure may be about 1 atmosphere. Ambient temperature may be a typical temperature to which humans are generally accustomed. For example, from about 15 °C to about 30 °C, from about -30 °C to about 60 °C, from about -20 °C to about 50 °C, from 16 °C to about 26 °C, from about 20 °C to about 25 °C. “Room temperature” may be measured in a confined or in a non-confined space. For example, “room temperature” can be measured in a room, an office, a factory, a vehicle, a container, or outdoors. The vehicle may be a car, a truck, a bus, an airplane, a space shuttle, a spaceship, a ship, a boat, or any other vehicle. Room temperature may represent the small range of temperatures at which the atmosphere feels neither hot nor cold, approximately 24 °C. it may denote 20 °C, 25 °C, or any value from about 20 °C to about 25 °C. [0119] In some embodiments, the 3D printer has a capacity to complete at least 1 , 2, 3, 4, or 5 printing cycles before requiring human intervention. Human intervention may be required for refilling the pre-transformed (e.g., powder) material, unloading the build modules, unpacking the 3D object, removing the debris byproduct of the 3D printing, or any combination thereof. The 3D printer operator may condition the 3D printer at any time during operation of the 3D printing system (e.g., during the 3D printing process). Conditioning of the 3D printer may comprise refilling the pre-transformed material that is used by the 3D printer, replacing gas source, or replacing filters. The conditioning may be with or without interrupting the 3D printing system. For example, refilling and unloading from the 3D printer can be done at any time during the 3D printing process without interrupting the 3D printing process. Conditioning may comprise refreshing the 3D printer.

[0120] In some embodiments, the 3D printer comprises an energy source that generates an energy beam. The energy beam may project energy to the material bed. The apparatuses, systems, and/or methods described herein can comprise at least one energy beam. In some cases, the 3D printing system can comprise at least two, three, four, five, eight, twelve, sixteen, twenty four, thirty two, or more energy beams. The energy beam may include radiation comprising electromagnetic, electron, positron, proton, plasma, or ionic radiation. The electromagnetic beam may comprise microwave, infrared, ultraviolet or visible radiation. The ion beam may include a cation or an anion. The electromagnetic beam may comprise a laser beam. The energy beam may derive from a laser source, in some embodiments, the energy source is an energy beam source. The energy source (e.g., Fig. 1 , 121) may be a laser source. The laser may comprise a fiber laser, a solid-state laser or a diode laser (e.g., diode pumped fiber laser). [0121] In some embodiments, the energy source is a laser source. The laser source may comprise a Nd: YAG, Neodymium (e.g., neodymium-glass), or an Ytterbium laser. The laser beam may comprise a corona laser beam, e.g., a laser beam having a footprint similar to a doughnut shape or a ring shape. The laser may comprise a carbon dioxide laser (CO₂ laser). The laser may be a fiber laser. The laser may be a solid-state laser. The laser can be a diode laser. The energy source may comprise a diode array. The energy source may comprise a diode array laser. The laser may be a laser used for micro laser sintering. Examples of 3D printing systems, apparatuses, devices, and components (e.g., energy beams), controllers, software, and 3D printing processes can be found in International Patent Application Serial No.

PCT/US17/60035, filed November s, 2017; and in International Patent Application Serial No. PCT/US22/16550, filed February 26, 2022; each of which is entirely incorporated herein by reference.

[0122] In some embodiments, the energy beam (e.g., transforming energy beam) comprises a Gaussian energy beam. The energy beam may have any cross-sectional shape comprising an ellipse (e.g., circle), or a polygon (e.g., as disclosed herein). The energy beam may be continuous or non-continuous (e.g., pulsing). The energy beam may be modulated before and/or during the formation of a transformed material as part of the 3D object. The energy beam may be modulated before and/or during the 3D printing process. In some embodiments, the energy beam (e.g., laser) has a power of at least about 150Watt (W), 200W, 250W, 300W, 350W, 400W, 500W, 750W, 800W, 900W, 1000W, 1500W, 2000W, 3000W, or 4000W. The energy source may have a power between any of the afore-mentioned energy beam power values (e.g., from about from about 150W to about 1000W, or from about 1000W to about 4000W) . The energy beam may derive from an electron gun.

[0123] In some embodiments, the 3D printer includes a plurality of energy beam, e.g., laser beams. The 3D printer may comprise at least 2, 4, 6, 8, 10, 12, 16, 20, 24, 32, 36, 64, or more energy beams. Each of the energy beam may be coupled with its own optical window. At times, at least two energy beams may shine through the same optical window. At times, at least two energy beams may shine through different optical windows.

[0124] In some embodiments, the energy beam (e.g., transforming energy beam) comprises a Gaussian energy beam. The energy beam may have any cross-sectional shape comprising an ellipse (e.g., circle), or a polygon (e.g., as disclosed herein). The energy beam may be continuous or non-continuous (e.g., pulsing). The energy beam may be modulated before and/or during the formation of a transformed material as part of the 3D object. The energy beam may be modulated before and/or during the 3D printing process.

[0125] In some embodiments, the beam profile of the energy beam is altered, e.g., during printing. Any of the 3D printing methodologies disclosed herein can include altering the beam profile. Alteration of the beam profile can be using a physical component and/or a computational scheme (e.g., algorithm). Alteration of the beam profile can comprise manual and/or automatic methods. The automatic methods may comprise usage of at least one controller directing the beam profile alteration. The beam profile may be altered during the 3D printing, e.g., during printing of a layer of transformed material that forms at least a portion of the 3D object.

Alteration of the beam profile can comprise alteration of a type of an energy profile utilized. The type of the beam profile comprises: a gaussian beam profile, a top hat beam profile, or a ring (e.g., corona or doughnut) beam profile. For example, the energy beam may print a first portion of the 3D object using a gaussian beam profile, and then print a second portion of the 3D object using a ring shaped beam profile.

[0126] In some embodiments, an energy beam is utilized for the 3D printing. The methods, apparatuses and/or systems disclosed herein may comprise Q-switching, mode coupling or mode locking to effectuate the pulsing energy beam. The apparatus or systems disclosed herein may comprise an on/off switch, a modulator, or a chopper to effectuate the pulsing energy beam. The on/off switch can be manually or automatically controlled. The switch may be controlled by the control system. The switch may alter the “pumping power” of the energy beam. The energy beam may be at times focused, non-focused, or defocused. In some instances, the defocus is substantially zero (e.g., the beam is non-focused). In some embodiments, the energy source(s) projects energy using a digital light processing (DLP) modulator, a one-dimensional scanner, a two-dimensional scanner, or any combination thereof. The energy source(s) can be stationary or translatable. The energy source(s) can translate vertically, horizontally, or in an angle (e.g., planar or compound angle). The energy source(s) can be modulated. The energy beam(s) emitted by the energy source(s) can be modulated. The modulator can include an amplitude modulator, phase modulator, or polarization modulator. The modulation may alter the intensity of the energy beam. The modulation may alter the current supplied to the energy source (e.g., direct modulation). The modulation may affect the energy beam (e.g., external modulation such as external light modulator). The modulation may include direct modulation (e.g., by a modulator). The modulation may include an external modulator. The modulator can include an acousto-optic modulator or an electro-optic modulator. The modulator can comprise an absorptive modulator or a refractive modulator. The modulation may alter the absorption coefficient the material that is used to modulate the energy beam. The modulator may alter the refractive index of the material that is used to modulate the energy beam. In some embodiments, a scanning speed of an energy beam may be at least about 50 millimeters per second (mm/sec), 100 mm/sec, 500 mm/sec, 1000 mm/sec, 2000 mm/sec, 3000 mm/sec, 4000 mm/sec, or 50000 mm/sec. The scanning speed of the scanning energy beam may be at most about 50 mm/sec, 100 mm/sec, 500 mm/sec, 1000 mm/sec, 2000 mm/sec, 3000 mm/sec, 4000 mm/sec, or 50000 mm/sec. The scanning speed of the scanning energy beam may be any value between the aforementioned values (e.g., from about 50 mm/sec to about 50000 mm/sec, from about 50 mm/sec to about 3000 mm/sec, or from about 2000 mm/sec to about 50000 mm/sec). The scanning energy beam may be continuous or non-continuous (e.g., pulsing).

[0127] In some embodiments, the energy beam (e.g., laser beam) impinges onto an exposed surface of a material bed to generate at least a portion of a 3D object. The energy beam may be a focused beam. The energy beam may be a dispersed beam. The energy beam may be an aligned beam. The apparatus and/or systems described herein may comprise a focusing coil, a deflection coil, or an energy beam power supply.

[0128] In some embodiments, the 3D printer comprises a power supply. The power supply to any of the components described herein can be supplied by a grid, generator, local, or any combination thereof. The power supply can be from renewable or non-renewable sources. The renewable sources may comprise solar, wind, hydroelectric, or biofuel. The power supply can comprise rechargeable batteries.

[0129] In some embodiments, the 3D printer comprises at least one controller, e.g., as part of a control system (such as any control system disclosed herein). The controller(s) may control one or more characteristics of the energy beam (e.g., variable characteristics). The control of the energy beam may allow a lower degree of material evaporation during the 3D printing process that would have otherwise transpire. The material evaporation may form debris (e.g., gas borne debris). The at least one controller may be part of a control system. The control system may be a hierarchical control system. The control system may include at least three hierarchical control levels. The control system may comprise a microcontroller.

[0130] In some cases, the 3D printing system can comprise two, three, four, five, eight, ten, sixteen, eighteen, twenty, twenty four, thirty two, or more energy sources that each generates an energy beam (e.g., laser beam). An energy source can be a source configured to deliver energy to an area (e.g., a confined area). An energy source can deliver energy to the confined area through radiative heat transfer. The energy source may comprise a laser source or an electron beam source.

[0131] In some embodiments, the energy source generates any of the energies described herein (e.g., energy beams). The energy source may deliver energy to a point or to an area, e.g., at a target surface. The energy source may include an electron gun source. The energy source may include a laser source. The energy source may comprise an array of energy sources (e.g., laser source array). In an example, a laser can provide light energy at a peak wavelength of at least about 100 nanometer (nm), 500 nm, 1000 nm, 1010 nm, 1020nm, 1030 nm, 1040 nm, 1050 nm, 1060 nm, 1070 nm, 1080 nm, 1090 nm, 1100 nm, 1200 nm, 1500 nm, 1600 nm, 1700 nm, 1800 nm, 1900 nm, or 2000 nm. In an example a laser can provide light energy at a peak wavelength of at most about 100 nanometer (nm), 500 nm, 1000 nm, 1010 nm, 1020nm, 1030 nm, 1040 nm, 1050 nm, 1060 nm, 1070 nm, 1080 nm, 1090 nm, 1100 nm, 1200 nm, 1500 nm, 1600 nm, 1700 nm, 1800 nm, 1900 nm, or 2000 nm. In an example a laser can provide light energy at a peak wavelength between the afore-mentioned peak wavelengths (e.g., from 100nm to 2000 nm, from 100nm to 1100nm, or from 1000 nm to 2000 nm). The energy beam can be incident on the exposed surface of the material bed. The energy beam can be incident on, or be directed to, a specified area of the material bed over a specified time period. The energy beam can be substantially perpendicular to the exposed (e.g., top) surface of the material bed. The material bed can absorb the energy from the energy beam (e.g., incident energy beam) and, as a result, a localized region of the material in the material bed can increase in temperature. The increase in temperature may transform the material within the material bed. The increase in temperature may heat and transform the material within the material bed. In some embodiments, the increase in temperature may heat and not transform the material within the material bed. The increase in temperature may heat the material within the material bed.

[0132] In some embodiments, the energy beam is moveable with respect to a material bed and/or 3D printing system. The energy beam can be moveable such that it can translate relative to the material bed. The energy beam can be moved by an optical system (e.g., comprising a scanner). The movement of the energy beam can comprise utilization of a scanner. In some embodiments, the energy source is stationary.

[0133] In some embodiments, the formation of the 3D object includes transforming (e.g., fusing, binding and/or connecting) the pre-transformed material (e.g., 3D printing starting material such as a powder material) using an energy beam. The energy beam may be projected on to the starting material (e.g., disposed in the material bed), thus causing the pre-transformed material to transform (e.g., fuse). The energy beam may cause at least a portion of the pretransformed material to transform from its present state of matter to a different state of matter. For example, the pre-transformed material may transform at least in part (e.g., completely) from a solid to a liquid state. The energy beam may cause at least a portion of the pre-transformed material to chemically transform. For example, the energy beam may cause chemical bonds to form or break. The chemical transformation may be an isomeric transformation. The transformation may comprise a magnetic transformation or an electronic transformation. The transformation may comprise coagulation of the material, cohesion of the material, or accumulation of the material. Transformation of the material may comprise connecting disconnected starting materials. For example, connecting various powder particles. The connection may comprise phase transfer, or chemical bonding. The connection may comprise fusing the starting material, e.g., sintering or melting the starting material.

[0134] In some embodiments, the methods described herein comprise repeating the operations of material deposition and material transformation operations to produce (e.g., print) a 3D object (or a portion thereof) by at least one 3D printing (e.g., additive manufacturing) method. For example, the methods described herein may comprise repeating the operations of depositing a layer of pre-transformed material and transforming at least a portion of the pretransformed material to connect to the previously formed 3D object portion (e.g., repeating the 3D printing cycle), thus forming at least a portion of a 3D object. The transforming operation may comprise utilizing energy beam(s) to transform the material. In some instances, the energy beam is utilized to transform at least a portion of the material bed.

[0135] In some embodiments, the transforming energy is provided by an energy source. The transforming energy may comprise an energy beam. The energy source can produce an energy beam. The energy beam may include a radiation comprising electromagnetic, electron, positron, proton, plasma, or ionic radiation. The electromagnetic beam may comprise microwave, infrared, ultraviolet, or visible radiation. The ion beam may include a charged particle beam. The ion beam may include a cation, or an anion. The electromagnetic beam may comprise a laser beam. The laser may comprise a fiber, or a solid-state laser beam. The energy source may include a laser. The energy source may include an electron gun. The energy depletion may comprise heat depletion. The energy depletion may comprise cooling. The energy may comprise an energy flux (e.g., energy beam. E.g., radiated energy). The energy may comprise an energy beam. The energy may be the transforming energy. The energy may be a warming energy that is not able to transform the deposited pre-transformed material (e.g., in the material bed). The warming energy may be able to raise the temperature of the deposited pre-transformed material. The energy beam may comprise energy provided at a (e.g., substantially) constant or varied energy beam characteristics. The energy beam may comprise energy provided at (e.g., substantially) constant or varied energy beam characteristics, depending on the position of the generated hardened material within the 3D object. The varied energy beam characteristics may comprise energy flux, rate, intensity, wavelength, amplitude, power, cross-section, or time exerted for the energy process (e.g., transforming or heating). The energy beam footprint may be the average (or mean) FLS of the footprint of the energy beam on the exposed surface of the material bed. The FLS may be a diameter, a spherical equivalent diameter, a length, a height, a width, or diameter of a bounding circle. The FLS may be the larger of a length, a height, and a width of a 3D form.

[0136] In some embodiments, the term “auxiliary support,” as used herein, generally refers to at least one feature that is a part of a printed 3D object, but not part of the requested, intended, designed, ordered, and/or final 3D object. Auxiliary support may provide structural support during and/or after the formation of the 3D object. The auxiliary support may be anchored to the enclosure. For example, an auxiliary support may be anchored to the platform (e.g., building platform such as a build plate), to the side walls of the material bed, to a wall of the enclosure, to an object (e.g., stationary or semi-stationary) within the enclosure, or any combination thereof. The auxiliary support may be the platform (e.g., the base, or the substrate) or the bottom of the enclosure. The auxiliary support may enable the removal or energy from the 3D object (e.g., or a portion thereof) that is being formed. The removal of energy (e.g., heat) may be during and/or after the formation of the 3D object. Examples of auxiliary support comprise a fin (e.g., heat fin), anchor, handle, pillar, column, frame, footing, wall, platform, or another stabilization feature. In some instances, the auxiliary support may be mounted, clamped, or situated on the platform. The auxiliary support can be anchored to the building platform, to the sides (e.g., walls) of the building platform, to the enclosure, to an object (stationary or semi-stationary) within the enclosure, or any combination thereof.

[0137] In some examples, the generated 3D object(s) can be printed without auxiliary support in a material bed in which it/they are formed. In some examples, low hanging overhanging feature an/or hollow cavities of the generated 3D object can be printed without (e.g., without any) auxiliary support. The low overhanging features may be shallow overhanging features with respect to an exposed surface of the material bed. The low overhanging features may form an angle of at most about 40 degrees (°), 35 °, or 25 ° with the exposed surface of the material bed (or a plane parallel thereto). The printed 3D object can be devoid of auxiliary supports. The printed 3D object may be suspended (e.g., float anchorlessly) in the material bed (e.g., powder bed). The term “anchorlessly,” as used herein, generally refers to without, or in the absence of, an auxiliary anchor. In some examples, an object is suspended in a material bed anchorlessly without attachment to a support. For example, the object floats in the material bed. A portion of the printed 3D object can be devoid of auxiliary supports. The portion of the 3D object may be suspended over a volume of the material bed. For example, a portion of the object defines an enclosed cavity which may be temporarily filled with powder material during a build process. The generated 3D object may be suspended in the layer of pre-transformed material (e.g., powder material). The pre-transformed material can offer support to the printed 3D object (or the object during its generation). Sometimes, the generated 3D object may comprise one or more auxiliary supports. The auxiliary support may be suspended in the pre-transformed material (e.g., powder material). The auxiliary support may provide weight or stabilizer. The auxiliary support can be suspended in the material bed such as within the layer of pre-transformed material in which the 3D object (or a portion thereof) has been formed. The auxiliary support may touch the platform. The auxiliary support may be suspended in the material bed and not touch (e.g., contact) the platform. The auxiliary support may be anchored to the platform.

[0138] In some examples, the at least 3D object may be generated above a platform, which at least one 3D object comprises auxiliary supports. In some examples, the auxiliary support(s) adhere to the upper surface of the platform. In some examples, the auxiliary supports of the printed 3D object may touch the platform (e.g., the bottom of the enclosure, the substrate, or the base). Sometimes, the auxiliary support may adhere to the platform. In some embodiments, the auxiliary supports are an integral part of the platform. At times, auxiliary support(s) of the printed 3D object, do not touch the platform. In any of the methods described herein, the printed 3D object may be supported only by the pre-transformed material within the material bed (e.g., powder bed, Fig. 1 , material bed 104). Any auxiliary support(s) of the printed 3D object, if present, may be suspended adjacent to the platform. Occasionally, the platform may have a prehardened (e.g., pre-solidified) amount of material. Such pre-solidified material may provide support to the printed 3D object. At times, the platform may provide adherence to the material. At times, the platform does not provide adherence to the material. The platform may comprise elemental metal, metal alloy, elemental carbon, or ceramic. The platform may comprise a composite material (e.g., as disclosed herein). The platform may comprise glass, stone, zeolite, or a polymeric material. The polymeric material may include a hydrocarbon or fluorocarbon. The platform (e.g., base) may include Teflon. The platform may include compartments for printing small objects. Small may be relative to the size of the enclosure. The compartments may form a smaller compartment within the enclosure, which may accommodate a layer of pre-transformed material.

[0139] In some examples, when the energy source is in operation, the material bed reaches a certain (e.g., average) temperature. The average temperature of the material bed can be an ambient temperature or “room temperature.” The average temperature of the material bed can have an average temperature during the operation of the energy (e.g., beam(s)). The average temperature of the material bed can be an average temperature during the formation of the transformed material, the formation of the hardened material, or the generation of the 3D object. The average temperature can be below or just below the transforming temperature of the material. Just below can refer to a temperature that is by at most about 1 °C, 2 °C, 3 °C, 4 °C, 5 °C, 6 °C, 7 °C, 8 °C, 9 °C, 10 C, 15 °C, or 20 °C below the transforming temperature. The average temperature of the material bed (e.g., pre-transformed material) can be by at most about 25 °C (degrees Celsius), 50 °C, 100 °C, 150 °C, 200 °C, 250 °C, 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C, 900 °C, 1000 °C, 1200 °C, 1400 °C, 1600 °C, 1800 °C, or 2000 °C. The average temperature of the material bed (e.g., pre-transformed material) can be at least about 20 °C, 25 °C, 50 °C, 100 °C, 150 °C, 200 °C, 250 °C, 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C, 900 °C, 1000 °C, 1200 °C, 1400 °C, 1600 °C, or 1800 °C. The average temperature of the material bed (e.g., of the pre-transformed material therein) can be any temperature between the afore-mentioned material average temperatures. The average temperature of the material bed can be below a melting point of the material constituting the material bed. The average temperature of the material bed can be above an ambient temperature external to the enclosure in which the material bed is disposed. The average temperature of the material bed (e.g., pretransformed material therein) may refer to the average temperature during the 3D printing. The pre-transformed material can be the material within the material bed that has not been transformed and generated at least a portion of the 3D object (e.g., the remainder). The temperature of the material bed can be conditioned (e.g., heated or cooled) before, during, or after forming (e.g., printing) the 3D object (e.g., hardened material). Bulk heaters can heat and/or cool the material bed. The bulk temperature conditioners can be situated adjacent to (e.g., above, below, or to the side of) the material bed, or within a material dispensing system. For example, the material can be heated using radiators (e.g., quartz radiators, or infrared emitters). The material bed temperature can be controller (e.g., substantially maintained) at a predetermined value. The temperature of the material bed can be monitored. The material temperature can be controlled manually and/or by a control system (e.g., such as any control system disclosed herein).

[0140] In some embodiments, the 3D printing system comprises one or more sensors. The 3D printing system includes at least one enclosure. In some embodiments, the 3D printing system (e.g., its enclosure) comprises one or more sensors (alternatively referred to herein as one or more sensors). The enclosure described herein may comprise at least one sensor. The enclosure may comprise, or be operatively coupled to, the build module, the filtering mechanism, gas recycling system, the processing chamber, or the ancillary chamber. The sensor may be connected and/or controlled by the control system (e.g., computer control system, or controller(s)). The control system may be able to receive signals from the at least one sensor. The control system, e.g., through a control scheme, may act upon at least one signal received from the at least one sensor. The control scheme may comprise a feedback and/or feed forward control scheme, e.g., that has been pre-programmed. The feedback and/or feed forward control may rely on input from at least one sensor that is connected to the controller(s). [0141] In some embodiments, the 3D printing system comprises one or more sensors. The one or more sensors can comprise a pressure sensor, a temperature sensor, a gas flow sensor, or an optical density sensor. The pressure sensor may measure the pressure of the chamber (e.g., pressure of the chamber atmosphere). The pressure sensor can be coupled to the control system. The pressure can be electronically and/or manually controlled. The controller may regulate the pressure (e.g., with the aid of one or more vacuum pumps) according to input from at least one pressure sensor. The sensor may comprise light sensor, image sensor, acoustic sensor, vibration sensor, chemical sensor, electrical sensor, magnetic sensor, fluidity sensor, movement sensor, speed sensor, position sensor, pressure sensor, force sensor, density sensor, metrology sensor, sonic sensor (e.g., ultrasonic sensor), or proximity sensor. The metrology sensor may comprise measurement sensor (e.g., height, length, width, depth, angle, and/or volume). The metrology sensor may comprise a magnetic, acceleration, orientation, or optical sensor. The optical sensor may comprise a camera (e.g., IR camera, or CCD camera (e.g., single line CCD camera)), or CCD camera (e.g., single line CCD camera). The sensor may transmit and/or receive sound (e.g., echo), magnetic, electronic, or electromagnetic signal. The electromagnetic signal may comprise a visible, infrared, ultraviolet, ultrasound, radio wave, or microwave signal. The metrology sensor may measure the tile. The metrology sensor may measure the gap. The metrology sensor may measure at least a portion of the layer of material (e.g., pre-transformed, transformed, and/or hardened). The layer of material may be a pretransformed material (e.g., powder), transformed material, or hardened material. The metrology sensor may measure at least a portion of the 3D object. The sensor may comprise a temperature sensor, weight sensor, powder level sensor, gas sensor, or humidity sensor. The gas sensor may sense any gas enumerated herein. The temperature sensor may comprise Bolometer, Bimetallic strip, Calorimeter, Exhaust gas temperature gauge, Flame detection, Gardon gauge, Golay cell, Heat flux sensor, Infrared thermometer, Microbolometer, Microwave radiometer, Net radiometer, Quartz thermometer, Resistance temperature detector, Resistance thermometer, Silicon band gap temperature sensor, Special sensor microwave/imager, Temperature gauge, Thermistor, Thermocouple, Thermometer, Pyrometer, IR camera, or CCD camera (e.g., single line CCD camera). The temperature sensor may measure the temperature without contacting the material bed (e.g., non-contact measurements). The pyrometer may comprise a point pyrometer, or a multi-point pyrometer. The Infrared (IR) thermometer may comprise an IR camera. The pressure sensor may comprise Barograph, Barometer, Boost gauge, Bourdon gauge, hot filament ionization gauge, Ionization gauge, McLeod gauge, Oscillating U-tube, Permanent Downhole Gauge, Piezometer, Pirani gauge, Pressure sensor, Pressure gauge, tactile sensor, or Time pressure gauge. The position sensor may comprise Auxanometer, Capacitive displacement sensor, Capacitive sensing, Free fall sensor, Gravimeter, Gyroscopic sensor, Impact sensor, Inclinometer, Integrated circuit piezoelectric sensor, Laser rangefinder, Laser surface velocimeter, LIDAR, Linear encoder, Linear variable differential transformer (LVDT), Liquid capacitive inclinometers, Odometer, Photoelectric sensor, Piezoelectric accelerometer, Rate sensor, Rotary encoder, Rotary variable differential transformer, Selsyn, Shock detector, Shock data logger, Tilt sensor, Tachometer, Ultrasonic thickness gauge, Variable reluctance sensor, or Velocity receiver. The optical sensor may comprise a Charge-coupled device, Colorimeter, Contact image sensor, Electro-optical sensor, Infra-red sensor, Kinetic inductance detector, light emitting diode as light sensor, Light- addressable potentiometric sensor, Nichols radiometer, Fiber optic sensors, optical position sensor, photo detector, photodiode, photomultiplier tubes, phototransistor, photoelectric sensor, photoionization detector, photomultiplier, photo resistor, photo switch, phototube, scintillometer, Shack-Hartmann, single-photon avalanche diode, superconducting nanowire single-photon detector, transition edge sensor, visible light photon counter, or wave front sensor. The weight of the enclosure (e.g., container), or any components within the enclosure can be monitored by at least one weight sensor in or adjacent to the material. For example, a weight sensor can be situated at the bottom of the enclosure. The weight sensor can be situated between the bottom of the enclosure and the substrate. The weight sensor can be situated between the substrate and the base. The weight sensor can be situated between the bottom of the container and the base. The weight sensor can be situated between the bottom of the container and the top of the material bed. The weight sensor can comprise a pressure sensor. The weight sensor may comprise a spring scale, a hydraulic scale, a pneumatic scale, or a balance. At least a portion of the pressure sensor can be exposed on a bottom of the container. In some cases, the at least one weight sensor can comprise a button load cell. Alternatively, or additionally a sensor can be configured to monitor the weight of the material by monitoring a weight of a structure that contains the material (e.g., a material bed). One or more position sensors (e.g., height sensors) can measure the height of the material bed relative to the substrate. The position sensors can be optical sensors. The position sensors can determine a distance between one or more energy sources and a surface of the material bed. The surface of the material bed can be the upper surface of the material bed. For example, Fig. 1 , 119 shows an example of an exposed (e.g., upper) surface of the material bed 104.

[0142] In some embodiments, the 3D printer comprises one or more valves. The methods, systems and/or the apparatus described herein may comprise at least one valve. The valve may be shut or opened according to an input from the at least one sensor, or manually. The degree of valve opening or shutting may be regulated by the control system, for example, according to at least one input from at least one sensor. The systems and/or the apparatus described herein can include one or more valves, such as throttle valves. The valve may or may not comprise a sensor sensing the open/shut position of the valve. The valve may be a component of a gas flow mechanism, e.g., operable to control a flow of gas of the gas flow mechanism. A valve may be a component of gas flow assembly, e.g., operable to control a flow of gas of the gas flow assembly.

[0143] In some embodiments, the 3D printer comprises one or more actuators such as motors. The motor may be controlled by the controller(s) (e.g., by the control system) and/or manually. The motor may alter (e.g., the position of) the substrate and/or to the base. The motor may alter (e.g., the position of) the elevator. The actuator may facilitate translation (e.g., propagation) of the layer dispenser, e.g., the actuator may facilitate reversible translation of the layer dispenser. The motor may alter an opening of the enclosure (e.g., its opening or closure). The motor may be a step motor or a servomotor. The actuator (e.g., motor) may alter (e.g., a position of) one or more optical components, e.g., mirrors, lenses, prisms, and the like. The servomotors may comprise actuated linear lead screw drive motors. The motors may comprise belt drive motors. The motors may comprise rotary encoders. The encoder may comprise an absolute encoder. The encoder may comprise an incremental encoder. The apparatuses and/or systems may comprise switches. The switches may comprise homing or limit switches. The motors may comprise actuators. The motors may comprise linear actuators. The motors may comprise belt driven actuators. The motors may comprise lead screw driven actuators. The actuators may comprise linear actuators.

[0144] In some embodiments, the 3D printer (e.g., its components) comprises one or more nozzles. The systems and/or the apparatus described herein may comprise at least one nozzle. For example, the material remover may comprise a nozzle. The nozzle may be regulated according to at least one input from at least one sensor. The nozzle may be controlled automatically or manually. The controller(s) may control the nozzle. The controller(s) may any controller(s) disclosed herein, e.g., as part of the control system of the 3D printer. The nozzle may include jet (e.g., gas jet) nozzle, high velocity nozzle, propelling nozzle, magnetic nozzle, spray nozzle, vacuum nozzle, or shaping nozzle (e.g., a die). The nozzle can be a convergent or a divergent nozzle. The spray nozzle may comprise an atomizer nozzle, an air-aspirating nozzle, or a swirl nozzle. The material dispenser can comprise a nozzle, e.g., through which material is removed from the material bed. The gas flow system may comprise a nozzle, e.g., that facilitates adjustment to the gas flow. The optical window may be supported by a nozzle that directs debris away from the optical window, e.g., at towards the material bed. The nozzle may comprise a venturi nozzle.

[0145] In some embodiments, the 3D printer comprises one or more pumps. The systems and/or the apparatus described herein may comprise at least one pump. The pump may be regulated according to at least one input from at least one sensor. The pump may be controlled automatically or manually. The controller may control the pump. The one or more pumps may comprise a positive displacement pump. The positive displacement pump may comprise rotarytype positive displacement pump, reciprocating-type positive displacement pump, or linear-type positive displacement pump.

[0146] In some embodiments, the 3D printer comprises a communication technology. The communication may comprise wired or wireless communication. For example, the systems, apparatuses, and/or parts thereof may comprise Bluetooth, wi-fi, global positioning system (GPS), or radio-frequency (RF) technology. The RF technology may comprise ultrawideband (UWB) technology. Systems, apparatuses, and/or parts thereof may comprise a communication port. The communication port may be a serial port or a parallel port. The communication port may be a Universal Serial Bus port (i.e., USB). The systems, apparatuses, and/or parts thereof may comprise USB ports. The USB can be micro or mini-USB. The surface identification mechanism may comprise a plug and/or a socket (e.g., electrical, AC power, DC power). The systems, apparatuses, and/or parts thereof may comprise an electrical adapter (e.g., AC and/or DC power adapter). The systems, apparatuses, and/or parts thereof may comprise a power connector. The power connector can be an electrical power connector. The power connector may comprise a magnetically attached power connector. The power connector can be a dock connector. The connector can be a data and power connector. The connector may comprise pins. The connector may comprise at least about 10, 15, 18, 20, 22, 24, 26, 28, 30, 40, 42, 45, 50, 55, 80, or 100 pins.

[0147] In some embodiments, the 3D printer comprises a controller. The controller may monitor and/or direct (e.g., physical) alteration of the operating conditions of the apparatuses, software, and/or methods described herein. The controller may be a manual or a non-manual controller. The controller may be an automatic controller. The controller may operate upon request. The controller may be a programmable controller. The controller may be programed. The controller may comprise a processing unit (e.g., CPU or GPU). The controller may receive an input (e.g., from a sensor). The controller may deliver an output. The controller may be part of a control system comprising multiple controllers. The controller may receive multiple inputs. The controller may generate multiple outputs. The controller may be a single input single output controller (SISO) or a multiple input multiple output controller (MIMO). The controller may interpret the input signal received. The controller may acquire data from the one or more sensors. Acquire may comprise receive or extract. The data may comprise measurement, estimation, determination, generation, or any combination thereof. The controller may comprise feedback control. The controller may comprise feed-forward control. The control may comprise on-off control, proportional control, proportional-integral (PI) control, or proportional-integral- derivative (PID) control. The control may comprise open loop control, or closed loop control. The controller may comprise closed loop control. The controller may comprise open loop control. The controller may utilize one or more wired and/or wireless networks for communication, e.g., with other controllers or devices, apparatuses, or systems of the 3D printing system and its components. For example, wired ethernet technologies, e.g., a local area networks (LAN). For example, wireless communication technologies, e.g., a wireless local area network (WLAN). The controller may utilize one or more control protocols for communication, for example, with other controller(s) or one or more devices, apparatuses, or systems of the 3D printing system or any of its components. Control protocols can comprise one or more protocols of an internet protocol suite, e.g., transmission control protocol (TCP) or transmission control protocol/internet protocol (TCP/IP). Control protocols can comprise one or more serial communication protocols. Control protocols can comprise one or more of controller area networks or another message-based protocol, e.g., for communication with microcontrollers and devices. Control protocols can interface with one or more serial bus interfaces for communication with the 3D printing system and its components. The controller may comprise a user interface. The user interface may comprise a keyboard, keypad, mouse, touch screen, microphone, speech recognition package, camera, imaging system, or any combination thereof. The outputs may include a display (e.g., screen), speaker, or printer. Examples of controller, control protocols, control systems, 3D printing systems, apparatuses, devices, and any of their components, and 3D printing processes can be found in International Patent Application Serial No. PCT/US17/18191 , filed February 16, 2017, titled “ACCURATE THREE-DIMENSIONAL PRINTING,” which is incorporated herein by reference in their entirety.

[0148] Control may comprise regulate, modulate, adjust, maintain, alter, change, govern, manage, restrain, restrict, direct, guide, oversee, manage, preserve, sustain, restrain, temper, or vary.

[0149] In some embodiments, the methods, systems, device, software and/or the apparatuses described herein comprise a control system. The control system can be in communication with one or more energy sources, optical systems, gas flow system, material flow systems, energy (e.g., energy beams) and/or with any other component of the 3D printing system. At least two of the energy sources may be of the same type or of different types. For example, at least two of the energy sources can be both fiber lasers. For example, the control system may be in communication with the first energy source and/or with the second energy source. The control system may regulate the one or more energy beams. The control system may regulate the energy supplied by the one or more energy sources. For example, the control system may regulate the energy supplied by a first energy beam and by a second energy beam, to the pretransformed material within the material bed. The control system may regulate the position of the one or more energy beams. For example, the control system may regulate the position of the first energy beam and/or the position of the second energy beam.

[0150] In some embodiments, a plurality of energy beams is used to transform the pretransformed material to print one or more 3D objects. At least a portion of the energy beams may be staggered, e.g., in a direction. The direction of may be along the direction of the gas flow, or at an angle relative to the direction of flow. The angle may be perpendicular, or an angle different than perpendicular. The plurality of energy beam may comprise at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, 24, or 32 energy beams. The plurality of energy beams may form an array. At least two energy beams of the plurality of energy beams may be controlled independently of each other. At least two energy beams of the plurality of energy beams may be controlled in concert. At least two energy beams of the plurality of energy beams may translate independently of each other. At least two energy beams of the plurality of energy beams may translate in concert. At least two energy beams of the plurality of energy beams may be controlled by the same controller. At least two energy beams of the plurality of energy beams may be controlled by different controllers.

[0151] In some embodiments, the 3D printer comprises at least one filter. The filter may be a ventilation filter. The ventilation filter may capture fine powder from the 3D printing system. The filter may comprise a paper filter such as a high-efficiency particulate air (HEPA) filter (a.k.a., high-efficiency particulate arresting filter). The ventilation filter may capture debris such as soot, splatter, or spatter. The debris may result from the 3D printing process. The ventilator may direct the debris in a requested direction (e.g., by using positive or negative gas pressure). For example, the ventilator may use vacuum. For example, the ventilator may use gas blow.

[0152] In some embodiments, the time lapse between the end of printing in a first material bed, and the beginning of printing in a second material bed is at most about 60minutes (min), 40min, 30min, 20min, 15min, 10min, or 5 min. The time lapse between the end of printing in a first material bed, and the beginning of printing in a second material bed may be between any of the afore-mentioned times (e.g., from about 60min to abo 5min, from about 60min to about 30min, from about 30min to about 5min, from about 20min to about 5 min, from about 20min to about 10 min, or from about 15 min to about 5min). Examples of the speed during which the 3D printing process proceeds, 3D printing systems, apparatuses, devices, and components, controllers, software, and 3D printing processes can be found in International Patent Application Serial No. PCT/US15/36802 that is incorporated herein in its entirety.

[0153] In some embodiments, the 3D object is removed from the material bed after the completion of the 3D printing process. For example, the 3D object may be removed from the material bed when the transformed material that formed the 3D object hardens. For example, the 3D object may be removed from the material bed when the transformed material that formed the 3D object is no longer susceptible to deformation under standard handling operation (e.g., human and/or machine handling). At times, the generated 3D object requires very little or no further processing after its retrieval. Further processing may be post printing processing. Further processing may comprise trimming, annealing, curing, or polishing, e.g., as disclosed herein. Further processing may comprise polishing such as sanding. In some cases, the generated 3D object can be retrieved and finalized without removal of transformed material and/or auxiliary support features.

[0154] In some examples, the generated 3D object adheres (e.g., substantially) to a requested model of the 3D object. The 3D object (e.g., solidified material) that is generated can have an average deviation value from the intended dimensions (e.g., of a requested 3D object) of at most about 0.5 microns (pm), 1 pm, 3 pm, 10 pm, 30 pm, 100 pm, 300 pm or less from a requested model of the 3D object. The deviation can be any value between the afore-mentioned values. The average deviation can be from about 0.5 pm to about 300 pm, from about 10 pm to about 50 pm, from about 15 pm to about 85 pm, from about 5 pm to about 45 pm, or from about 15 pm to about 35 pm. The 3D object can have a deviation from the intended dimensions in a specific direction, according to the formula D_v + — , wherein D_v is a deviation value, L is the Kdv length of the 3D object in a specific direction, and K_dv is a constant. D_v can have a value of at most about 300 pm, 200 pm, 100 pm, 50 pm, 40 pm, 30 pm, 20 pm, 10 pm, 5 pm, 1 pm, or 0.5 pm. D_v can have a value of at least about 0.5 pm, 1 pm, 3 pm, 5 pm, 10 pm, 20 pm, 30 pm, 50 pm, 70 pm, 100 pm, 300 pm or less. D_v can have any value between the afore-mentioned values. For example, D_v can have a value that is from about 0.5 pm to about 300 pm, from about 10 pm to about 50 pm, from about 15 pm to about 85 pm, from about 5 pm to about 45 pm, or from about 15 pm to about 35 pm. K_dv can have a value of at most about 3000, 2500, 2000, 1500, 1000, or 500. /C_ducan have a value of at least about 500, 1000, 1500, 2000, 2500, or 3000. K_dv can have any value between the afore-mentioned values. For example, K_dv can have a value that is from about 3000 to about 500, from about 1000 to about 2500, from about 500 to about 2000, from about 1000 to about 3000, or from about 1000 to about 2500.

[0155] At times, the generated 3D object (i.e., the printed 3D object) does not require further processing following its generation by a method described herein. The printed 3D object may require reduced amount of processing after its generation by a method described herein. For example, the printed 3D object may not require removal of auxiliary support (e.g., since the printed 3D object was generated as a 3D object devoid of auxiliary support). The printed 3D object may not require smoothing, flattening, polishing, or leveling. The printed 3D object may not require further machining. In some examples, the printed 3D object may require one or more treatment operations following its generation (e.g., post generation treatment, or post printing treatment). The further treatment step(s) may comprise surface scraping, machining, polishing, grinding, blasting (e.g., sand blasting, bead blasting, shot blasting, or dry ice blasting), annealing, or chemical treatment. The further treatment may comprise physical or chemical treatment. The further treatment step(s) may comprise electrochemical treatment, ablating, polishing (e.g., electro polishing), pickling, grinding, honing, or lapping. In some examples, the printed 3D object may require a single operation (e.g., of sand blasting) following its formation. The printed 3D object may require an operation of sand blasting following its formation.

Polishing may comprise electro polishing (e.g., electrochemical polishing or electrolytic polishing). The further treatment may comprise the use of abrasive(s). The blasting may comprise sand blasting or soda blasting. The chemical treatment may comprise use or an agent. The agent may comprise an acid, a base, or an organic compound. The further treatment step(s) may comprise adding at least one added layer (e.g., cover layer). The added layer may comprise lamination. The added layer may be of an organic or inorganic material. The added layer may comprise elemental metal, metal alloy, ceramic, or elemental carbon. The added layer may comprise at least one material that composes the printed 3D object. When the printed 3D object undergoes further treatment, the bottom most surface layer of the treated object may be different than the original bottom most surface layer that was formed by the 3D printing (e.g., the bottom skin layer).

[0156] At times, the methods described herein are performed in the enclosure (e.g., container, processing chamber, and/or build module). One or more 3D objects can be formed (e.g., generated, and/or printed) in the enclosure (e.g., simultaneously, and/or sequentially). The enclosure may have a predetermined and/or controlled pressure. The enclosure may have a predetermined and/or controlled atmosphere. The control may be manual or via a control system.

[0157] In some examples, the enclosure comprises an atmosphere having an ambient pressure (e.g., 1 atmosphere), or positive pressure. The atmosphere may have a negative pressure (i.e., vacuum). Different portions of the enclosure may have different atmospheres. The different atmospheres may comprise different gas compositions. The different atmospheres may comprise different atmosphere temperatures. The different atmospheres may comprise ambient pressure (e.g., 1 atmosphere), negative pressure (i.e., vacuum) or positive pressure. The different portions of the enclosure may comprise the processing chamber, build module, or enclosure volume excluding the processing chamber and/or build module. The vacuum may comprise pressure below 1 bar, or below 1 atmosphere. The positively pressurized environment may comprise pressure above 1 bar or above 1 atmosphere. In some cases, the chamber pressure can be standard atmospheric pressure. The pressure may be measured at an ambient temperature (e.g., room temperature, 20°C, or 25°C).

[0158] In some embodiments, the enclosure includes an atmosphere. The enclosure may comprise a (e.g., substantially) inert atmosphere. The atmosphere in the enclosure may be (e.g., substantially) depleted by one or more gases present in the ambient atmosphere. The atmosphere in the enclosure may include a reduced level of one or more gases relative to the ambient atmosphere. For example, the atmosphere may be substantially depleted, or have reduced levels of water (i.e., humidity), oxygen, nitrogen, carbon dioxide, hydrogen sulfide, or any combination thereof. The level of the depleted or reduced level gas may be at most about 0.1 parts per million (ppm), 1 ppm, 3 ppm, 10 ppm, 50 ppm, 100 ppm, 500 ppm, 1000 ppm, 3000 ppm, or 5000 ppm volume by volume (v/v). The level of the depleted or reduced level gas may be at least about 1 ppm, 10 ppm, 50 ppm, 100 ppm, 500 ppm, 1000 ppm, or 5000 ppm (v/v). The level of the oxygen gas may be at most about 1 ppm, 10 ppm, 50 ppm, 100 ppm, 500 ppm, 1000 ppm, or 2000 ppm (v/v). The level of the water vapor may be at most about 1 ppm, 10 ppm, 50 ppm, 100 ppm, 500 ppm, 700 ppm, 800 ppm, 900 ppm, or 1000 ppm, (v/v). The level of the gas (e.g., depleted or reduced level gas, oxygen, or water) may be between any of the afore-mentioned levels of gas. The atmosphere may comprise air. The atmosphere may be inert. The atmosphere in the enclosure (e.g., processing chamber) may have reduced reactivity (e.g., be non-reactive) as compared to the ambient atmosphere external to the processing chamber and/or external to the printing system. The atmosphere may have reduced reactivity with the material (e.g., the pre-transformed material deposited in the layer of material (e.g., powder) or with the material comprising the 3D object), which reduced reactivity is compared to the reactivity of the ambient atmosphere. The atmosphere may hinder (e.g., prevent) oxidation of the generated 3D object, e.g., as compared to the oxidation by an ambient atmosphere external to the 3D printer and/or processing chamber. The atmosphere may hinder (e.g., prevent) oxidation of the pre-transformed material within the layer of pre-transformed material before its transformation, during its transformation, after its transformation, before its hardening, after its hardening, or any combination thereof. The atmosphere may comprise an inert gas. For example, the atmosphere may comprise argon or nitrogen gas. The atmosphere may comprise a Nobel gas. The atmosphere can comprise a gas selected from the group consisting of argon, nitrogen, helium, neon, krypton, xenon, hydrogen, carbon monoxide, and carbon dioxide. The atmosphere may comprise hydrogen gas. The atmosphere may comprise a safe amount of hydrogen gas. The atmosphere may comprise a v/v percent of hydrogen gas of at least about 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, or 5%, at ambient pressure (e.g., and ambient temperature). The atmosphere may comprise a v/v percent of hydrogen gas of at most about 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, or 5%, at ambient pressure (e.g., and ambient temperature). The atmosphere may comprise any percent of hydrogen between the afore-mentioned percentages of hydrogen gas. The atmosphere may comprise a v/v hydrogen gas percent that is at least able to react with the material (e.g., at ambient temperature and/or at ambient pressure), and at most adhere to the prevalent work-safety standards in the jurisdiction (e.g, hydrogen codes and standards). The material may be the material within the layer of pre-transformed material (e.g., powder), the transformed material, the hardened material, or the material within the 3D object. Ambient refers to a condition to which people are generally accustomed. For example, ambient pressure may be about one (1) atmosphere.

[0159] In some embodiments, the apparatus and/or systems described herein comprise an optical system. The optical components may be controlled manually and/or via a control system (e.g., a controller). Fig. 2 shows an example of an optical system. The optical system may be configured to direct at least one energy beam (e.g., 207) from the at least one energy source (e.g., 206) to a position on a target surface such as an exposed surface of a material bed within the enclosure, e.g., to a predetermined position on the target surface. A scanner can be included in the optical system. The 3D printing system may comprise a processor (e.g., a central processing unit). The processor can be programmed to control a trajectory of the at least one energy beam and/or energy source with the aid of the optical system. The systems and/or the apparatus described herein can comprise a control system in communication with the at least one energy source and/or energy beam. The control system can regulate a supply of energy from the at least one energy source to the material in the container. The control system may control the various components of the optical system (e.g., Fig. 2). The various components of the optical system may include optical components comprising a mirror(s) (e.g., 205), a lens (e.g., concave or convex), a fiber, a beam guide, a rotating polygon, or a prism. The lens may be a focusing or a dispersing lens. The lens may be a diverging or converging lens. The mirror can be a deflection mirror. The optical components may be tiltable and/or rotatable. The optical components may be tilted and/or rotated. The mirror may be a deflection mirror. The optical components may comprise an aperture. The aperture may be mechanical. The optical system may comprise a variable focusing device. The variable focusing device may be connected to the control system. The variable focusing device may be controlled by the control system and/or manually. The variable focusing device may comprise a modulator. The modulator may comprise an acousto-optical modulator, mechanical modulator, or an electro optical modulator. The focusing device may comprise an aperture (e.g., a diaphragm aperture). The energy beam may be directed through a window (e.g., an optical window 204) to a target surface (e.g., 202). The optical window may be part of a chamber (e.g., processing chamber) of a printing system. [0160] In some embodiments, the 3D printing system comprises a processor. The processor may be a processing unit. The controller may comprise a processing unit. The processing unit may be central. The processing unit may comprise a central processing unit (herein “CPU”). The controllers or control mechanisms (e.g., comprising a computer system) may be programmed to implement methods of the disclosure. The processor (e.g., 3D printer processor) may be programmed to implement methods of the disclosure. The controller may control at least one component of the systems and/or apparatuses disclosed herein. Fig. 3 is a schematic example of a computer system 300 that is programmed or otherwise configured to facilitate the formation of a 3D object according to the methods provided herein. The computer system 300 can control (e.g., direct, monitor, and/or regulate) various features of printing methods, apparatuses and systems of the present disclosure, such as, for example, control force, translation, heating, cooling and/or maintaining the temperature of a powder bed, process parameters (e.g., chamber pressure), scanning rate (e.g., of the energy beam and/or the platform), scanning route of the energy source, position and/or temperature of the cooling member(s), application of the amount of energy emitted to a selected location, or any combination thereof. The computer system 301 can be part of, or be in communication with, a 3D printing system or apparatus. The computer may be coupled to one or more mechanisms disclosed herein, and/or any parts thereof. For example, the computer may be coupled to one or more sensors, valves, switches, motors, pumps, scanners, optical components, or any combination thereof. The computer system 300 can include a processing unit 306 (also “processor,” “computer” and “computer processor” used herein). The computer system may include memory or memory location 302 (e.g., randomaccess memory, read-only memory, flash memory), electronic storage unit 304 (e.g., hard disk), communication interface 303 (e.g., network adapter) for communicating with one or more other systems, and peripheral devices 305, such as cache, other memory, data storage and/or electronic display adapters. The memory 302, storage unit 304, interface 303, and peripheral devices 305 are in communication with the processing unit 306 through a communication bus (solid lines), such as a motherboard. The storage unit can be a data storage unit (or data repository) for storing data. The computer system can be operatively coupled to a computer network (“network”) 301 with the aid of the communication interface. The network can be the Internet, an internet and/or extranet, or an intranet and/or extranet that is in communication with the Internet. In some cases, the network is a telecommunication and/or data network. The network can include one or more computer servers, which can enable distributed computing, such as cloud computing. The network, in some cases with the aid of the computer system, can implement a peer-to-peer network, which may enable devices coupled to the computer system to behave as a client or a server. The processing unit can execute a sequence of machine- readable instructions, which can be embodied in a program or software. The instructions may be stored in a memory location, such as the memory 302. The instructions can be directed to the processing unit, which can subsequently program or otherwise configure the processing unit to implement methods of the present disclosure. Examples of operations performed by the processing unit can include fetch, decode, execute, and write back. The processing unit may interpret and/or execute instructions. The processor may include a microprocessor, a data processor, a central processing unit (CPU), a graphical processing unit (GPU), a system-on-chip (SOC), a co-processor, a network processor, an application specific integrated circuit (ASIC), an application specific instruction-set processor (ASIPs), a controller, a programmable logic device (PLD), a chipset, a field programmable gate array (FPGA), or any combination thereof. The processing unit can be part of a circuit, such as an integrated circuit. One or more other components of the system 300 can be included in the circuit.

[0161] In some embodiments, the storage unit 304 stores files, such as drivers, libraries, and saved programs. The storage unit can store user data (e.g., user preferences and user programs). In some cases, the computer system can include one or more additional data storage units that are external to the computer system, such as located on a remote server that is in communication with the computer system through an intranet or the Internet. The processor may be configured to process control protocols, e.g., communicate with one or more components of the 3D printer system using the control protocols. Control protocols can be one or more of the internet protocol suite, e.g., transmission control protocol (TCP) or transmission control protocol/internet protocol (TCP/IP). Control protocols can be one or more of serial communication protocols. Control protocols can be one or more of controller area networks or another message-based protocol, e.g., for communication with microcontrollers and devices. Control protocols can interface with one or more serial bus interfaces for communication with the 3D printing system and its components. The control protocol can be any control protocol disclosed herein.

[0162] In some embodiments, the 3D printer comprises communicating through a network. The computer system can communicate with one or more remote computer systems through a network. For instance, the computer system can communicate with a remote computer system of a user (e.g., operator). Examples of remote computer systems include personal computers (e.g., portable PC), slate or tablet PC’s (e.g., Apple® iPad, Samsung® Galaxy Tab), telephones, Smart phones (e.g., Apple® iPhone, Android-enabled device, Blackberry®), or personal digital assistants. A user (e.g., client) can access the computer system via the network.

[0163] In some embodiments, the computer system utilizes program instructions to execute, or direct execution of, operation(s). The program instructions can be inscribed in a machine executable code. Methods as described herein can be implemented by way of machine (e.g., computer processor) executable code stored on an electronic storage location of the computer system, such as, for example, on the memory 302 or electronic storage unit 304. The machine executable or machine-readable code can be provided in the form of software. During use, the processor 306 can execute the code. In some cases, the code can be retrieved from the storage unit and stored on the memory for ready access by the processor. In some situations, the electronic storage unit can be precluded, and machine-executable instructions are stored on memory. The code can be pre-compiled and configured for use with a machine have a processer adapted to execute the code, or can be compiled during runtime. The code can be supplied in a programming language that can be selected to enable the code to execute in a pre-compiled or as-compiled fashion.

[0164] At times, the energy beam follows a path. The path of the energy beam may be a vector. The path of the energy beam may comprise a raster, a vector, or any combination thereof. The path of the energy beam may comprise an oscillating pattern. The path of the energy beam may comprise a zigzag, wave (e.g., curved, triangular, or square), or curve pattern. The curved wave may comprise a sine or cosine wave. The path of the energy beam may comprise a sub-pattern. The path of the energy beam may comprise an oscillating (e.g., zigzag), wave (e.g., curved, triangular, or square), and/or curved sub-pattern. The curved wave may comprise a sine or cosine wave.

[0165] At times, the energy (e.g., energy beam) travels in a path. The path may comprise a hatch, e.g., path 401 of Fig. 4. The path of the energy beam may comprise repeating a path. For example, the first energy may repeat its own path. The second energy may repeat its own path, or the path of the first energy. The repetition may comprise a repetition of 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 times or more. The energy may follow a path comprising parallel lines. For example, Fig. 5, 515 or 514 show paths that comprise parallel lines. The lines may be hatch lines. The distance between each of the parallel lines or hatch lines, may be at least about 1 pm, 5 pm, 10 pm, 20 pm, 30 pm, 40 pm, 50 pm, 60 pm, 70 pm, 80 pm, 90 pm, or more. The distance between each of the parallel lines or hatch lines, may be at most about 1 pm, 5 pm, 10 pm, 20 pm, 30 pm, 40 pm, 50 pm, 60 pm, 70 pm, 80 pm, 90 pm, or less. The distance between each of the parallel lines or hatch lines may be any value between any of the afore-mentioned distance values (e.g., from about 1 pm to about 90 pm, from about 1 pm to about 50 pm, or from about 40 pm to about 90 m). The distance between the parallel or parallel lines or hatch lines may be substantially the same in every layer (e.g., plane) of transformed material. The distance between the parallel lines or hatch lines in one layer (e.g., plane) of transformed material may be different than the distance between the parallel lines or hatch lines respectively in another layer (e.g., plane) of transformed material within the 3D object. The distance between the parallel lines or hatch lines portions within a layer (e.g., plane) of transformed material may be substantially constant. The distance between the parallel lines or hatch lines within a layer (e.g., plane) of transformed material may be varied. The distance between a first pair of parallel lines or hatch lines within a layer (e.g., plane) of transformed material may be different than the distance between a second pair of parallel lines or hatch lines within a layer (e.g., plane) of transformed material respectively. The first energy beam may follow a path comprising two hatch lines or paths that cross in at least one point. Fig. 4 shows an example of a path 401 of an energy beam comprising a zigzag sub-pattern (e.g., 402 shown as an expansion (e.g., blow-up) of a portion of the path 401). The sub-path of the energy beam may comprise a wave (e.g., sine or cosine wave) pattern. The sub-path may be a small path that forms the large path. The sub-path may be a component (e.g., a portion) of the large path. The path that the energy beam follows may be a predetermined path. A model may predetermine the path by utilizing a controller or an individual (e.g., human). The controller may comprise a processor. The processor may comprise a computer, computer program, drawing or drawing data, statue or statue data, or any combination thereof. The hatch lines or paths may be straight or curved. The hatch lines or paths may be winding. Fig. 5, 55 or 511 show examples of winding paths. The first energy beam may follow a hatch line or path comprising a U-shaped turn (e.g., Fig. 5, 55) and/or looping turn (e.g., Fig. 5, 516). The first energy beam may follow a hatch line or path devoid of U-shaped turns (e.g., Fig. 512).

[0166] At times, the path comprises successive lines. The successive lines may touch each other. The successive lines may overlap each other in at least one point. The successive lines may substantially overlap each other. The successive lines may be spaced by a first distance (e.g., hatch spacing). Fig. 5 shows an example of a path 514 that includes five hatches wherein each two immediately adjacent hatches are separated by a spacing distance. Examples of 3D printing systems, apparatuses, devices, and any component thereof; controllers, software, and 3D printing processes (e.g., hatch spacings) can be found in International Patent Application Serial No PCT/US 16/34857 filed on May 27, 2016, titled “THREE-DIMENSIONAL PRINTING AND THREE-DIMENSIONAL OBJECTS FORMED USING THE SAME” that is entirely incorporated herein by reference.

[0167] The present disclosure provides systems, apparatuses, software, and/or methods for 3D printing of a requested (e.g., desired) 3D object from a pre-transformed material (e.g., powder material). The 3D object (or portions thereof) can be pre-ordered, pre-designed, premodeled, or designed in real time (e.g., during the process of 3D printing). For example, the object may be designed as part of the print preparation process of the 3D printing. For example, various portion of the object may be designed as other parts of that object are being printed. Real time is during formation of at least one of: 3D object, a layer of the 3D object, dwell time of an energy beam along a path, dwell time of an energy beam along a hatch line, dwell time of an energy beam forming a tile, and dwell time of an energy beam forming a melt pool. The fundamental length scale (e.g., the diameter, spherical equivalent diameter, diameter of a bounding circle, or the largest of height, width and length; abbreviated herein as “FLS”) of the printed 3D object can be at least about 50 micrometers (pm), 80 pm, 100 pm, 120 pm, 150 pm, 170 pm, 200 pm, 230 pm, 250 pm, 270 pm, 300 pm, 400 pm, 500 pm, 600 pm, 700 pm, 800 pm, 1 millimeter (mm), 1.5mm, 2mm, 5mm, 1 centimeter (cm), 1.5cm, 2cm, 10cm, 20cm, 30cm, 40cm, 50cm, 60cm, 70cm, 80cm, 90cm, 1m, 2m, 3m, 4m, 5m, 10m, 50m, 80m, or 100m. The FLS of the printed 3D object can be at most about 1000m, 500m, 100m, 80m, 50m, 10m, 5m, 4m, 3m, 2m, 1 m, 90cm, 80cm, 60cm, 50cm, 40cm, 30cm, 20cm, 10cm, or 5cm. In some cases, the FLS of the printed 3D object may be in between any of the afore-mentioned FLSs (e.g., from about 50 pm to about 1000m, from about 120 pm to about 1000m, from about 120 pm to about 10m, from about 200 pm to about 1 m, or from about 150 pm to about 10m).

[0168] In some embodiments, at least a portion of a printed 3D object is deformed. In some embodiments, a newly formed layer of material (e.g., comprising transformed material) reduces in volume during its hardening (e.g., by cooling). Such reduction in volume (e.g., shrinkage) may cause a deformation in the requested 3D object. The deformation may include cracks, and/or tears in the newly formed layer and/or in other (e.g., adjacent) layers. The deformation may include geometric deformation of the 3D object or at least a portion thereof. The newly formed layer can be a portion of a 3D object. The one or more layers that form the 3D Printed object (e.g., sequentially) may be (e.g., substantially) parallel to the building platform. An angle may be formed between a layer of hardened material of the 3D printed object and the platform. The angle may be measured relative to the average layering plane of the layer of hardened material. The platform (e.g., building platform) may include the base, substrate, or bottom of the enclosure. The building platform may be a carrier plate.

[0169] In an aspect provided herein is a 3D object comprising a layer of hardened material generated by at least one 3D printing method described herein, wherein the layer of material (e.g., hardened) is different from a corresponding cross section of a model of the 3D object. For example, the generated layers differ from the proposed slices. The layer of material within a 3D object can be indicated by the microstructure of the material. Examples of 3D printing systems, apparatuses, devices, and any component thereof; controllers, software, 3D printing processes, printer 3D objects and their material microstructures can be found in International Patent Application serial number PCT/US15/36802 that is incorporated herein by reference in its entirety. [0170] In some examples, the 3D object is a large 3D object. In some embodiments, the 3D object comprises a large hanging structure (e.g., wire, ledge, or shelf). Large may be a 3D object having a fundamental length scale of at least about 1 centimeter (cm), 1.5cm, 2cm, 10cm, 20cm, 30cm, 40cm, 50cm, 60cm, 70cm, 80cm, 90cm, 1 m, 2m, 3m, 4m, 5m, 10m, 50m, 80m, or 100m. The hanging structure may be a thin structure. The hanging structure may be a plane like structure (referred to herein as “three-dimensional plane,” or “3D plane”). The 3D plane may have a relatively small width as opposed to a relatively large surface area. For example, the 3D plane may have a small height relative to a large horizontal plane. Fig. 27 shows an example of a 3D plane that is planar. The 3D plane may be planar, curved, or assume an amorphous 3D shape. The 3D plane may be a strip, a blade, or a ledge. The 3D plane may comprise a curvature. The 3D plane may be curved. The 3D plane may be planar (e.g., flat). The 3D plane may have a shape of a curving scarf.

[0171] In some embodiments, the 3D object comprises a first portion and a second portion. The first portion may be connected to the rest of the 3D object at one, two, or three sides (e.g., as viewed from the top). The second portion may be connected to the rest of the 3D object at one, two, or three sides (e.g., as viewed from the top). For example, the first and second portion may be connected to a (e.g., central) column, post, or wall of the 3D object. For example, the first and second portion may be connected to an external cover that is a part of the 3D object. The first and/or second portion may be a wire or a 3D plane. The first and/or second portion may be different from a wire or 3D plane. The first and/or second portion may be a blade (e.g., turbine or impeller blade). The first portion may comprise a top surface. Top may be in the direction away from the platform and/or opposite to the gravitational field. The second portion may comprise a bottom surface (e.g., bottom skin surface). Bottom may be in the direction towards the platform and/or in the direction of the gravitational field. Fig. 6 shows an example of a first (e.g., top) surface 610 and a second (e.g., bottom) surface 620. At least a portion of the first and second surfaces are separated by a gap. At least a portion of the first surface is separated by at least a portion of the second surface (e.g., to constitute a gap). The gap may be filled with pre-transformed or transformed (e.g., and subsequently hardened) material during the formation of the 3D object. The second surface may be a bottom skin layer. Fig. 6 shows an example of a vertical gap distance 640 that separates the first surface 610 from the second surface 620. The vertical gap distance may be equal to the distance disclosed herein between two adjacent 3D planes. The vertical gap distance may be equal to the vertical distance of the gap as disclosed herein. Point A may reside on the top surface of the first portion. Point B may reside on the bottom surface of the second portion. The second portion may be a cavity ceiling or hanging structure as part of the 3D object. Point B may reside above point A. The gap may be the (e.g., shortest) distance (e.g., vertical distance) between points A and B. Fig. 6 shows an example of the gap 640 that constitutes the shortest distance d_AB between points A and B. There may be a first normal to the bottom surface of the second portion at point B. Fig. 6 shows an example of a first normal 612 to the surface 620 at point B. The angle between the first normal 612 and a direction of the gravitational acceleration vector 600 (e.g., direction of the gravitational field, or direction towards the gravitational center) may be any angle y. Point C may reside on the bottom surface of the second portion. There may be a second normal to the bottom surface of the second portion at point C. Fig. 6 shows an example of the second normal 622 to the surface 620 at point C. The angle between the second normal 622 and the direction of the gravitational acceleration vector 600 may be any angle 6. Vectors 611 , and 621 are parallel to the gravitational acceleration vector 600. The angles y and 6 may be the same or different. The angle between the first normal 612 and/or the second normal 622 to the direction of the gravitational acceleration vector 600 may be any angle alpha. The angle between the first normal 612 and/or the second normal 622 with respect to the normal to the substrate may be any angle alpha. The angles y and 6 may be any angle alpha. For example, alpha may be at most about 45 °, 40 °, 30 °, 20 °, 10 °, 5 °, 3 °, 2 °, 1 °, or 0.5 °. The shortest distance between points B and C may be any value of the auxiliary support feature spacing distance mentioned herein. For example, the shortest distance BC (e.g., d_BC) may be at least about 0.1 millimeters (mm), 0.5 mm, 1 mm, 1.5 mm, 2 mm, 3 mm, 4 mm, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm 35 mm, 40 mm, 50 mm, 100 mm, 200 mm, 300 mm, 400 mm, or 500 mm. As another example, the shortest distance BC may be at most about 500 mm, 400 mm, 300 mm, 200 mm, 100 mm, 50 mm, 40 mm, 35 mm, 30 mm, 25 mm, 20 mm, 15 mm, 10 mm, 5 mm, 4 mm, 3 mm, 2 mm, 1 .5 mm, 1 mm, 0.5 mm, or 0.1 mm. Fig. 6 shows an example of the shortest distance BC (e.g., 630, d_BC).

[0172] In some embodiments, the printed 3D object comprises at least one layer of hardened material. The layer of hardened material may have a curvature. The curvature can be positive or negative with respect to the platform and/or the exposed surface of the material bed. Fig. 7 shows examples of a vertical cross sections in various layered structures. For example, layered structure (e.g., 3D object 712) comprises layer number 6 that has a curvature that is negative, as the volume (e.g., area in a vertical cross section of the volume) bound from the bottom of it to the platform 718 has a convex shape 719. Layer number 5 of 712 has a curvature that is negative. Layer number 6 of 712 has a curvature that is more negative (e.g., has a curvature of greater negative value) than layer number 5 of 712. Layer number 4 of 712 has a curvature that is (e.g., substantially) zero. Layer number 6 of 714 has a curvature that is positive. Layer number 6 of 712 has a curvature that is more negative than layer number 5 of 712, layer number 4 of 712, and layer number 6 of 714.

[0173] In some embodiments, the curvature of all the layers within the 3D object is from at most about 0.02 millimeters’¹ (i.e., 1 /millimeters). In some embodiments, the layers within the 3D object are substantially planar (e.g., flat). In some embodiments, all the layers of hardened material can have a curvature of at least about zero (i.e., a substantially planar layer) to at most about 0.02 millimeters’¹. The curvature can be at most about -0.05 mm^-1, -0.04 mm^-1, -0.02 mm^-1, -0.01 mm^-1, -0.005 mm^-1, -0.001 mm^-1, substantially zero mm^-1, 0.001 mm^-1, 0.005 mm^-1, 0.01 mm^-1, 0.02 mm^-1, 0.04 mm^-1, or 0.05 mm^-1. The curvature can be any value between the afore-mentioned curvature values (e.g., from about -0.05 mm^-1 to about 0.05 mm^-1, from about -0.02 mm^-1 to about 0.005 mm^-1, from about -0.05 mm^-1 to substantially zero, or from about substantially zero to about 0.05 mm^-1). The curvature may refer to the curvature of a surface. The surface can be of the layer of hardened material (e.g., first layer). The surface may be of the 3D object (or any layer thereof).

[0174] The radius of curvature, “r,” of a curve at a point is a measure of the radius of the circular arc (e.g., Fig. 7, 716) which best approximates the curve at that point. The radius of curvature is the inverse of the curvature. In the case of a 3D curve (also herein a “space curve”), the radius of curvature is the length of the curvature vector. The curvature vector can comprise of a curvature (e.g, the inverse of the radius of curvature) having a particular direction. For example, the particular direction can be the direction to the platform (e.g., designated herein as negative curvature), or away from the platform (e.g., designated herein as positive curvature). For example, the particular direction can be the direction towards the direction of the gravitational field (e.g., designated herein as negative curvature), or opposite to the direction of the gravitational field (e.g., designated herein as positive curvature). A curve (also herein a “curved line”) can be an object similar to a line that is not required to be straight. A line can be a special case of curve wherein the curvature is substantially zero. A line of substantially zero curvature has a substantially infinite radius of curvature. The curve may represent a cross section of a curved plane. A line may represent a cross section of a flat (e.g., planar) plane. A curve can be in two dimensions (e.g., vertical cross section of a plane), or in three-dimension (e.g., curvature of a plane).

[0175] At times, the one or more layers within the 3D object may be substantially planar (e.g., flat). The planarity of the layer may be substantially uniform. The height of the layer at a particular position may be compared to an average plane. The average plane may be defined by a least squares planar fit of the top-most part of the surface of the layer of hardened material. The average plane may be a plane calculated by averaging the material height at each point on the top surface of the layer of hardened material. The deviation from any point at the surface of the planar layer of hardened material may be at most about 20% 15%, 10%, 5%, 3%, 1%, or 0.5% of the height (e.g., thickness) of the layer of hardened material. The substantially planar one or more layers may have a large radius of curvature. Fig. 7 shows an example of a vertical cross section of a 3D object 712 comprising planar layers (layers numbers 1-4) and non-planar layers (e.g., layers numbers 5-6) that have a radius of curvature. Fig. 7, 716 and 717 are superpositions of curved layer on a circle 715 having a radius of curvature “r.” The one or more layers may have a radius of curvature equal to the radius of curvature of the layer surface. The radius of curvature may equal infinity (e.g., when the layer is planar). The radius of curvature of the layer surface (e.g., all the layers of the 3D object) may have a value of at least about 0.1 centimeter (cm), 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm, 0.6 cm, 0.7cm, 0.8 cm, 0.9 cm, 1 cm, 5 cm, 10 cm, 20 cm, 30 cm, 40 cm, 50 cm, 60 cm, 70 cm, 80 cm, 90 cm, 1 meter (m), 1.5 m, 2 m, 2.5 m, 3 m, 3.5m, 4 m, 4.5 m, 5 m, 10 m, 15 m, 20 m, 25 m, 30 m, 50 m, or 100 m. The radius of curvature of the layer surface (e.g., all the layers of the 3D object) may have any value between any of the afore-mentioned values of the radius of curvature (e.g., from about 10 cm to about 90 m, from about 50 cm to about 10 m, from about 5 cm to about 1 m, from about 50 cm to about 5 m, from about 5 cm to infinity, or from about 40 cm to about 50 m). In some embodiments, a layer with an infinite radius of curvature is a layer that is planar. In some examples, the one or more layers may be included in a planar section of the 3D object, or may be a planar 3D object (e.g., a flat plane). In some instances, part of at least one layer within the 3D object has the radius of curvature mentioned herein.

[0176] At times, the 3D object may comprise a layered structure indicative of 3D printing process that is devoid of one or more auxiliary support features or one or more auxiliary support feature marks that are indicative of a presence or removal of the one or more auxiliary support features. The 3D object may comprise a layered structure indicative of 3D printing process, which includes one, two, or more auxiliary support marks. The supports or support marks can be on the surface of the 3D object. The auxiliary supports or support marks can be on an external, on an internal surface (e.g., a cavity within the 3D object), or both. The layered structure can have a layering plane. In one example, two auxiliary support features or auxiliary support feature marks present in the 3D object may be spaced apart by the auxiliary feature spacing distance. The acute (i.e., sharp) angle alpha between the straight line connecting the two auxiliary supports or auxiliary support marks and the direction of normal to the layering plane may be at least about 45 degrees (°), 50 °, 55 °, 60 °, 65 °, 70 °, 75 °, 80 °, or 85 °. The acute angle alpha between the straight line connecting the two auxiliary supports or auxiliary support marks and the direction of normal to the layering plane may be at most about 90 °, 85 °, 80 °, 75 °, 70 °, 65 °, 60 °, 55 °, 50 °, or 45 °. The acute angle alpha between the straight line connecting the two auxiliary supports or auxiliary support marks and the direction of normal to the layering plane may be any angle range between the afore-mentioned angles (e.g., from about 45 degrees (°), to about 90 °, from about 60 ° to about 90 °, from about 75 ° to about 90 °, from about 80 ⁰ to about 90 °, from about 85 ° to about 90 °). The acute angle alpha between the straight line connecting the two auxiliary supports or auxiliary support marks and the direction normal to the layering plane may from about 87 ° to about 90 °. An example of a layering plane can be seen in Fig. 7 showing a vertical cross section of a 3D object 711 that comprises layers 1 to 6, each of which are planar. In the schematic example in Fig. 7, the layering plane of the layers can be the layer. For example, layer 1 could correspond to both the layer and the layering plane of layer 1 . When the layer is not planar (e.g., Fig. 7, layer 5 of 3D object 712), the layering plane would be the average plane of the layer. The two auxiliary supports, or auxiliary support feature marks, can be on the same surface. The same surface can be an external surface or an internal surface (e.g., a surface of a cavity within the 3D object). When the angle between the shortest straight line connecting the two auxiliary supports or auxiliary support marks and the direction of normal to the layering plane is greater than 90 degrees, one can consider the complementary acute angle. In some embodiments, any two auxiliary supports, or auxiliary support marks, are spaced apart by the auxiliary feature spacing distance.

[0177] Fig. 8 shows a vertical cross section in a coordinate system. Line 804 represents a vertical cross section of the top surface of a platform. Line 803 represents a normal to the average layering plane. Line 802 represent the normal to the top surface of the platform. Line 801 represents the direction of the gravitational field pointing towards the gravitational center. The angle alpha in Fig. 8 is formed between the normal to the layering plane, and the top platform surface.

[0178] Fig. 9 shows an example of a 3D object 900 disposed on platform 903, which 3D object 900 comprises an exposed surface 901 that was formed with layers of hardened material (e.g., having layering plane 905) that are substantially planar and parallel to the platform 903. Fig. 9 shows an example of a 3D object 910 disposed on platform 913, which 3D object 910 comprises an exposed surface 911 that was formed with layers of hardened material (e.g., having layering plane 915) that are substantially planar and parallel to the platform 913 resulting in a tilted 3D object (e.g., box). 3D object 910 is tilted with respect to platform 913 by an angle beta (P) with respect to an axis 314 that is perpendicular to platform 913. Fig. 9 shows an example of a 3D object 920 disposed on platform 923. 3D object 920 was formed as a tilted 3D object during its formation, is shown lying flat on platform 923 as a 3D object having an exposed surface 921 and layers of hardened material (e.g., having layering plane 925) having a normal 924 to the layering plane that forms acute angle alpha (a) with the exposed surface 921 of the 3D object. 3D objects 900, 910, and 920 are disposed in relation to gravitational vector 999 directed towards gravitational center G.

[0179] In some embodiments, the 3D printer comprises at least one ancillary chamber. The ancillary chamber may be an integral part of the processing chamber. At times, the ancillary chamber may be separate (e.g., separable) from the processing chamber. The ancillary chamber may be mounted to the processing chamber (e.g., before, after, or during the 3D printing). The mounting may be reversible mounting. The mounting may be controlled (e.g., manually or by a controller). The atmosphere of the ancillary and processing chamber may be (e.g., substantially) the same atmosphere, e.g., during a printing operation. At times, the atmosphere of the ancillary chamber and the processing chamber may differ, e.g., during a printing operation. The atmosphere of the ancillary chamber may be an inert atmosphere, e.g., during a printing operation. The atmosphere in the ancillary chamber may be deficient by one or more reactive species (e.g., water and/or oxygen), e.g., during a printing operation. The ancillary chamber may be a garage. The garage may be used to house (e.g., park) one or more components of the 3D printer. The component may be a layer dispensing mechanism. The layer dispensing mechanism may be in the garage during operation of the energy beam(s), after dissension of a planar layer of starting material has been completed, during maintenance of the processing chamber, and/or during time sat which the layer dispenser is idle. The layer dispensing mechanism may be in a parked mode when the layer dispensing mechanism (or a portion thereof) is within the ancillary chamber and is not forming (e.g., dispensing, removing and/or shaping) a layer of starting material (e.g., pre-transformed material). The layer dispensing mechanism may be in a parked mode when it is (e.g., substantially) stationary (e.g., not translating and/or vibrating). The layer dispensing mechanism may be in a layer forming mode when the layer dispensing mechanism is forming (e.g., dispensing, removing and/or shaping) a layer of starting material (e.g., pre-transformed material) (e.g., in the processing chamber). One or more controllers can be configured to control at least one mode of the layer dispensing mechanism (e.g., layer forming mode and/or parked mode). The ancillary chamber (e.g., Fig. 10, 1054) may be coupled to one of the side walls of the processing chamber. In some embodiments, the ancillary chamber may be incorporated in the processing chamber. The processing chamber may be similar to the one described herein (e.g., Fig. 1 , 126). At times, the ancillary chamber may be a part of the processing chamber. At times, the ancillary chamber may be coupled to the processing chamber. The ancillary chamber may be mounted to the processing chamber. The mounting may be reversible mounting. The mounting may be controlled (e.g., manually or by a controller). The atmosphere of the ancillary chamber and processing chamber may be (e.g., substantially) the same atmosphere. At times, the atmosphere of the ancillary chamber and the processing chamber may differ.

[0180] In some embodiments, the 3D printer comprises an ancillary chamber. Fig. 10 shows an example of an ancillary chamber 1040 coupled to the processing chamber 1026 disposed in relation to gravitational vector 1099 directed towards gravitational center G. In some embodiments, the layer dispensing mechanism (e.g., 1034) is parked within the ancillary chamber, when the layer dispensing mechanism does not perform dispensing adjacent to a platform, which platform comprises a substrate 1061 and a base 1060. The layer dispensing mechanism may be conveyed to the processing chamber having an interior space (e.g., Fig. 10, 1026). When conveyed, the layer dispensing mechanism may move from a first position, e.g., a position within the ancillary chamber to a position adjacent to the build module (e.g., 1184). When conveyed, the one or more shafts may move from a first position (e.g., a position within the ancillary chamber) to a position adjacent to the processing chamber. When conveyed, the actuator may move from a first position (e.g., a position within the ancillary chamber) to a second position adjacent to the build module. When conveyed, the layer dispensing mechanism may dispense a layer of pre-transformed material adjacent to the platform to form a material bed (e.g., Fig. 10, 1004). The layer dispensing mechanism may park within the ancillary chamber. For example, the layer dispensing mechanism may part in the ancillary chamber when the layer dispensing mechanism is not performing a dispersion of a layer of pre-transformed material. For example, the layer dispensing mechanism may part in the ancillary chamber when the material dispenser does not dispense pre-transformed material. For example, the layer dispensing mechanism may part in the ancillary chamber when the material removal mechanism does planarize the material bed. For example, the layer dispensing mechanism may part in the ancillary chamber when the material bed is exposed to an energy beam (e.g., Fig. 10, 1001). [0181] In some embodiments, the ancillary chamber (e.g., also referred to herein as “ancillary enclosure,” e.g., 1054) is dimensioned to accommodate the layer dispensing mechanism (e.g., Fig. 10, 1034). The layer dispensing mechanism (layer dispenser) can include a material dispenser and a material remover. The ancillary chamber may be dimensioned to enclose the layer dispensing mechanism (layer dispensing mechanism), at least a portion of the one or more shafts (e.g., Fig. 10, 1036), or any combination thereof. In some cases, one section (e.g., first section) of the ancillary chamber is configured to house the layer dispensing mechanism (e.g., when the layer dispensing mechanism is in a parked mode) and another section (e.g., second section) of the ancillary chamber is configured to house the one or more actuators, e.g., that facilitate translation of the layer dispensing mechanism.

[0182] The layer dispensing mechanism may comprise at least one of a material dispensing mechanism (e.g., Fig. 1 , 116) and a material removal mechanism (e.g., Fig. 1 , 118). The ancillary chamber may be separated from the processing chamber through a closable opening that comprises a closure (e.g., a shield, door, or window). The opening (e.g., the partition between the ancillary chamber and the processing chamber) may comprise a closure (e.g., Fig. 10, 1056). The closure may relocate to allow the layer dispensing mechanism (also referred to herein as “layer dispenser,” or “layer dispensing mechanism”) to travel from the ancillary chamber to a position adjacent to (e.g., above) the material bed. The closure may be coupled with (e.g., connect to) the layer dispensing mechanism. The closure may be coupled with (e.g., connect to) at least one shaft that is coupled with (e.g., connect to) the layer dispensing mechanism. The closure may close to separate the processing chamber from the ancillary chamber within the same atmosphere (e.g., the processing chamber and ancillary chamber remain within the same atmosphere). The closure may close to isolate an atmosphere of the processing chamber from an atmosphere of the ancillary chamber. The closure may permit gaseous exchange between the processing chamber and the ancillary chamber. The closure may close to isolate operations in the processing chamber from components housed in the ancillary chamber (e.g., the layer dispenser). For example, the closure may close to isolate the 3D printing taking place in the processing chamber from components housed in the ancillary chamber (e.g., the layer dispenser). The closure may or may not close the opening when the layer dispensing mechanism is forming (e.g., dispensing, leveling, removing material from) a layer (e.g., is operative in the processing chamber). The closure may or may not close the opening when the energy beam is operative in the processing chamber. The closure may or may not close the opening when the pre-transformed material is being transformed to the transformed material. The closure may or may not close the opening when the layer dispensing mechanism is positioned within the ancillary chamber (e.g., when in the parked mode). The closure may open, e.g., to allow the atmosphere of the ancillary chamber and the processing chamber to merge. The closure may open, e.g., to allow debris from the processing chamber to enter the ancillary chamber. The closure may be (e.g., operatively) coupled to the layer dispensing mechanism. Operatively coupled may comprise physically coupled. The closure may be coupled via a mechanical connector, a controlled sensor, a magnetic connector, an electromagnetic connector, or an electrical connector. The layer dispensing mechanism may cause the closure to open when conveyed adjacent to the material bed (e.g., by pushing the closure). The closure may slide, tilt, flap, roll, or be pushed to allow the layer dispensing mechanism to travel to and from the ancillary chamber. The closure may relocate to a position adjacent to the opening. Adjacent may be below, above, to the side, or distant from the opening. Distant from the opening may comprise in a position more distant from the ancillary chamber. The closure may at least partially (e.g., fully) open the opening (e.g., before, after, and/or during the 3D printing). The closure may comprise an opaque, or a transparent material. The closure may comprise a reflective material. For example, the closure may comprise a mirror. The mirror may facilitate a user disposed outside of the processing chamber, to view operations taking place in the processing chamber, e.g., by looking at the mirror. The mirror may reflect the exposed surface of the material bed to the user, e.g., through viewing window(s) of the processing chamber.

[0183] In some examples, the 3D printer comprises a layer dispensing mechanism. Fig. 10 shows an example of a layer dispensing mechanism (e.g., Fig. 10, 1034) that can travel from a position in the ancillary chamber (e.g., Fig. 10, 1040) to a position adjacent to the material bed (e.g., Fig. 10, 1032). The separator (e.g., closure) may change its position to allow the movement of the layer dispensing mechanism to and/or from the ancillary chamber. The change of position may be by sliding, flapping, pushing, magnetic opening or rolling. For example, the separator may be a sliding, flapping, or rolling door. The separator may be operatively coupled to an actuator. The actuator may cause the separator to alter its position (e.g., as described herein). The actuator may cause the separator to slide, flap, or roll (e.g., in a direction). The direction may be up/down or sideways with respect to a prior position of the separator. The actuator may be controlled (e.g., by a controller and/or manually). Altering the position may be laterally, horizontally, or at an angle with respect to an exposed surface of the material bed and/or build platform. For example, the actuator may be controlled via at least one sensor (e.g., as disclosed herein). The sensor may comprise a position or motion sensor. The sensor may comprise an optical sensor. For example, the separator may be coupled to the layer dispensing mechanism. Coupling may be using mechanical, electrical, electro-magnetic, electrical, or magnetic connectors. The separator may slide, open or roll when pushed by the layer dispensing mechanism. The separator may slide, close or roll in place when the layer dispensing mechanism retracts into the ancillary chamber.

[0184] At times, the layer dispensing mechanism causes (e.g., directly, or indirectly) the closure to open and/or close the opening. Indirectly can be via at least one controller (e.g., comprising a sensor and/or actuator). Directly may comprise directly attached to the layer dispensing mechanism. Fig. 10 shows an example of an opening bordered by stoppers 1067, which opening is closed by a shield type closure 1056 that is connected to the layer dispensing mechanism 1034. In the example of Fig. 10, the layer dispensing opening causes the shield type closure to open the opening as the layer dispensing mechanism travels away from the ancillary chamber 1040 toward a position adjacent to the platform (e.g., comprising the base 1060). In the example of Fig. 10, the layer dispensing opening causes the shield type closure to close the opening as the layer dispensing mechanism travels into the ancillary chamber 1040 (e.g., to park).

[0185] At times, the layer dispensing mechanism is parked in the ancillary chamber. The layer dispensing mechanism may comprise a material removal mechanism that may include pretransformed material (e.g., starting material such as powder) and/or other debris (e.g., soot, spatter, splatter, or other debris). The debris may be dispersed on the floor of the ancillary chamber when the layer dispensing mechanism may be parked in the ancillary chamber. The (e.g., floor of the) ancillary chamber may be coupled to a recycling system. For example, the floor of the ancillary chamber may be coupled to the powder recycling system via a vacuum. The ancillary chamber may be coupled to a reconditioning system. The recycling and/or reconditioning system may comprise a sieve. The recycling system may comprise a reservoir that holds the recycled material. The recycled material may be reconditioned (e.g., having reduced level of reactive species such as oxygen, or water). The recycled material may be sieved through the sieving system. In some examples, material may not be reconditioned. The material may be pushed, attracted, and/or gravitationally removed from the ancillary chamber. For example, the material may be sucked by a vacuum, e.g., from the floor of the ancillary chamber. The ancillary chamber may be built to assist removal of the material by way of gravity. For example, the floor of the ancillary chamber may be tilted. For example, the ancillary chamber may be operatively coupled to a conveyance system that flows or bounces the material in a direction away from the ancillary chamber. The floor of the ancillary chamber may be sloped at an angle. The debris and material removed by the layer dispensing mechanism accumulated in the ancillary chamber may be transported away from the ancillary chamber (e.g., into the recycling system). Transportation may be via an opening port in the ancillary chamber. Transportation may be via a pipe, hole, channel, or a conveyor system. In some embodiments, the floor, a ceiling, or any other wall of the ancillary chamber includes one or more features to facilitate movement of the accumulated material through an opening port to the recycling system. The accumulated material may comprise the material removed by the layer dispensing mechanism, excess material and/or debris. At least a portion of the accumulated material may be removed from the layer dispensing mechanism, e.g., using the material remover.

[0186] In some embodiments, the layer dispensing mechanism is coupled to one or more shafts (e.g., a rod, a pole, a bar, a cylinder, one or more spherical bearings coupled at a predetermined distance) (e.g., Fig. 10, 1036). The one or more shafts may be movable. Moving of the shaft may facilitate movement of the layer dispensing mechanism operatively coupled to the shaft. For example, the shaft may be movable to and from the ancillary chamber and into the processing chamber (e.g., before, during, and/or after the 3D printing). Coupled may be physically attached to one of the components of the layer dispensing mechanism. The attachment may be physical, magnetic, electrical, or any combination thereof. The movement may be facilitated by a belt moving along a gear that is rotated by the actuator.

[0187] In some embodiments, a 3D printing system includes, or is operationally couple to, one or more gas recycling systems. The gas recycling system can be at least a portion of the gas flow mechanism. Fig. 11 shows a schematic side view of an example 3D printing system 1100 that is coupled to a gas recycling system 1103 in accordance with some embodiments. 3D printing system 1100 includes processing chamber 1102, which includes gas inlets 1104 and gas outlet 1105. The gas recycling system 1103 can be configured to recirculate the flow of gas from gas outlet 1105 back into processing chamber 1102 via the gas inlets 1104. Gas flow through channel 1106 exiting the gas outlet can include solid and/or gaseous contaminants such as debris (e.g., soot). Filtration system 1108 can be configured to filter out at least some of the solid and/or gaseous contaminants, thereby providing a clean gas (e.g., 1109) (e.g., cleaner than gas flow 1106). The filtration system can include one or more filters. The filters may comprise physical filters or chemical filters. The clean gas (e.g., 1109) exiting the filtering mechanism (also herein “filtration system") can be under lower pressure relative to the incoming gas pressure into the filtering mechanism. The lower pressure and the pressure of the incoming gas pressure may be above ambient pressure external to the 3D printing system. The clean gas can be directed through a pump (e.g., 1110) to regulate (e.g., increase) its relative pressure prior to entry to the processing chamber. Clean gas (e.g., 1111) with a regulated pressure that exits the pump can be directed through one or more sensors (e.g., 1112). The one or more sensors may comprise a flow meter, which can measure the flow (e.g., pressure) of the pressurized clean gas. The one or more sensors may comprise temperature, humidity, oxygen sensors, or any other sensor disclosed herein. In some cases, the clean gas can have an ambient pressure or higher. The higher pressure may provide a positive pressure within processing chamber (see example values of positive pressure described herein). A first portion of the clean gas can be directed through at least one inlet (e.g., inlets 1104) of a gas inlet portion of the enclosure, while a second portion of the clean gas can be directed to first and/or second window holders (e.g., 1114 and 1116) that provide gas purging of optical window areas, as described herein. That is, the gas recycling system can provide clean gas to provide a primary gas flow for the 3D printing system, as well as a secondary gas flow (e.g., window purging). In some embodiments, the pressurized clean gas is further filtered through a filter (e.g., 1117) prior to reaching one or both of the window holders. In some embodiments, the one or more filters (e.g., as part of filters 1117 and/or filtration system 1108) are configured to filter out particles having nanometer-scale (e.g., about 10 nm to about 500 nm) diameters. In some embodiments, the gas recycling system provides clean gas to a recessed portion (e.g., 1118) of the enclosure. In some embodiments, gas flow (e.g., 1150a and 1150b) from the recessed portion (e.g., 1118) of the enclosure can be directed through the gas recycling system (e.g., 1103). In some embodiments, gas flow from the recessed portion can be directed through one or more filters of a filtration system. In some embodiments, the gas recycling system provides clean gas directed to first and/or second window holders (e.g., 1114 and 1116).

[0188] Fig. 12 shows an example of a portion of a 3D printing system such as the one depicted in Fig. 10. Fig. 12 schematically depicts a pre-transformed material (e.g., starting material such as powder) conveyor system coupled to a processing chamber 1201 , having a layer dispensing mechanism (e.g., recoater) 1202. Pre-transformed material (e.g., powder) from a reservoir (e.g., hopper) 1203 can be introduced into the layer dispensing mechanism 1202. The layer dispensing mechanism is disposed in processing chamber 1201. Once the layer dispensing mechanism dispensers a layer of pre-transformed material to layerwise form a material bed utilized for the three-dimensional printing. In this process, excess pre-transformed material is attracted away from the material bed using layer dispensing mechanism 1202 and introduced into separator (e.g., cyclone) 1204, and optionally to overflow separator (e.g., cyclone) 1204. The pre-transformed material undergoes separation (e.g., cyclonic separation) in separators 1205 and optionally 1205, and is introduced into sieve 1206, followed by gravitational flow into a lower reservoir (e.g., hopper) 1207. The separated and sieved pre-transformed material is then delivered into separator (e.g., cyclone) 1208 and optional separator (e.g., cyclone) 1209, and into reservoir 1203 that delivers the pre-transformed material back into layer dispensing mechanism 1202. Fig. 12 shows examples of pumps (e.g., displacement pump and/or compressor) 1251 , 1252, 1253, and a temperature regulator (e.g., heater or radiator such as a radiant plane). Arrows in Fig. 12 depict direction of flow. In the channels facilitating the flow of the pre-transformed material, a venturi nozzle is introduced near junction 1222 to facilitate suction of the pre-transformed material from reservoir 1207 into separator 1208. A magnified view of junction 1222 is shown in 1222a, depicting venturi nozzle 1233 that is introduced in a channel opposing a gas inlet 1254 and normal to an inlet 1257 from which the pre-transformed material descends gravitationally towards gravitational center G along vector 1260. The conveyance system can include a condensed gas source (e.g., a blower or a cylinder of condensed gas) not shown. When the pre-transformed material descends towards junction 1222 from reservoir (e.g., hopper) 1207. The pre-transformed material is conveyed from junction 1222 to separator 1208. The conveyance system may include a heat exchanger. The conveyance system may include one or more filters. The conveyance system may operate at a positive pressure above ambient pressure external to the conveyance system (e.g., above about one atmosphere). In some embodiments, separator 1209 is coupled to sieve 1206 instead of to reservoir 1203.

[0189] Fig. 12 shows an example of at least a portion of a gas circulation system including channel marked with dotted line 1243, pumps 1252 and 1251 , and filter 1230. Fig. 12 shows an example of a first portion of a material conveyance system including channels marked with dotted line 1242 that convey material to and from the layer dispensing mechanism 1202 (e.g., recoater). Fig. 12 shows an example of a second portion of a material conveyance system including channels marked with dotted line 1241 that convey material in other portions of the material conveyance system, other than to and from the layer dispensing mechanism 1202. The gas circulating system may be configured to circulate (e.g. and recirculate) gas also in the processing chamber (e.g., 1201). The gas circulating system may sweep debris (e.g., soot) away from the process area in which the 3D object is being printed. The debris may collect on a filter (e.g., 1230), after which a cleaner gas is sent back (e.g., using a pump) through the channels of the gas circulation system (e.g., marked with dotted line 1243) to the processing chamber. In some embodiments, the 3D printer comprises one or more temperature adjusters (e.g., heat exchangers). For example, temperature adjusters operatively coupled to the gas circulation channel between pumps 1252 and 1251. For example, temperature adjusters operatively coupled to the material conveyance channel between pump 1251 and reservoir 1207. In some embodiments, the conveyance system of the pre-transformed material (e.g., powder) is in positive pressure above ambient pressure outside of the conveyance system and/or outside of the 3D printer. For example, the pressure in the 3D printer may be at least about 3 kilo Pascal (kPa), 5kPa, 8kPa, 10 kPa, 12 kPa, 14 kPa, 16 kPa, 18 kPa, or 20 kPa. That pressure may be controlled (e.g., maintained) in the processing chamber, gas conveying system, recycling system, ancillary chamber, and/or build module. At times, a pressure differential is required to convey pre-transformed material from one compartment of the 3D printer to another. The pressure differential may be established via pressurizing or vacuuming one or more compartments. For example, pre-transformed material from the layer dispensing system to the recycling system (e.g., including the separator(s), sieve(s), and/or reservoirs) may be conveyed using (a) induced pressure differential among components, (b) pressure isolation of the components, and (c) induced pressure equilibration of components.

[0190] In some embodiments, material utilized in the 3D printing undergoes passivation, e.g., using a passivation systems. A passivation system may comprise (A) an in-situ passivation system, (B) an ex-situ passivation system, or (C) a combination thereof. The passivation system may control a level of the oxidizing agent below a threshold. The oxidizing agent in the oxidizing mixture (e.g., oxygen) may be kept below a threshold (e.g. below 2000 ppm), e.g., by using one or more controllers such as the control system disclosed herein. The oxidizing agent in the oxidizing mixture may be kept below a threshold such that reaction of the gas mixture with the filter accumulated material (e.g., debris) is does not breakdown the filter media. The oxidizing agent in the oxidizing mixture may be kept below a threshold such that reaction of the gas mixture with the filter accumulated material (e.g., debris) does not exceed a temperature threshold (e.g., below about 200°C) at which the filter breaks down and/or releases oxidizing agent(s).

[0191] In some embodiments, the 3D printing system comprises an oxidizing agent, e.g., oxygen gas. In some embodiments, the oxidizing agent (e.g. oxygen) may be kept below a first threshold (e.g., to prevent reaction runway). In some embodiments, the oxidizing agent (e.g. oxygen) may be kept above a second threshold (e.g., to allow passivation). In some embodiments, the passivation mixture used to passivate the filter-accumulated material containing a diluent and at least one oxidizing agent (e.g., O₂ and/or water). At least one oxidizing agent in the mixture may be kept below the first threshold. The first threshold may be of at most 2000ppm, 1500ppm, WOOppm, 500ppm, 300ppm, 100ppm, or 50ppm of oxidizing agent (e.g., 02). The first threshold may be of at most any value of oxidizing agent between the aforementioned values (e.g., from 2000ppm to WOOppm, from 1500 ppm to 500ppm, from 500ppm, to 50ppm, or from 300ppm to 50ppm). At least one oxidizing agent in the mixture may be kept above the second threshold. The second threshold may be of at least about 0.5ppm, 1ppm, 2.5ppm, 5ppm, 10ppm, 25ppm, 50ppm, 75ppm, 100ppm, 300ppm, or 500ppm of oxidizing agent (e.g., O₂). The second threshold may be of at least any value of oxidizing agent between the aforementioned values (e.g., from 0.5ppm to 500ppm, from 0.5 ppm to 50ppm, from 25ppm, to 75ppm, or from 50ppm to 500ppm). A sensor (e.g. oxygen sensor) may be employed to provide information. The information (e.g., sensor data) may be utilized by the control system (e.g., by the control valve controller(s)) to control a requested (e.g. constant) level of the oxidizer in the passivation mixture. The first threshold (e.g., maximum oxidizing level threshold) may be higher in the ex-situ passivation system as compared to the in-situ passivation system. Higher may be by at least about 100ppm, 250ppm, or 500ppm. The second threshold (e.g., minimum oxidizing level threshold) may be higher in the ex-situ passivation system as compared to the in-situ passivation system. Higher may be by at least about 5ppm, 10ppm, or 50ppm.

[0192] In some embodiments, the gas in the gas conveyance system and/or enclosure comprises a robust gas. The robust gas may comprise an inert gas, e.g., enriched with reactive agent(s). The robust gas may comprise argon or nitrogen. At least one reactive agent in the robust gas may be in a concentration below that present in the ambient atmosphere external to the gas conveyance system and/or enclosure. The reactive agent(s) may comprise water or oxygen. The robust gas (e.g., gas mixture) may be more inert than the gas present in the ambient atmosphere. The robust gas may be less reactive than the gas present in the ambient atmosphere. Less reactive may be with debris, and/or pre-transformed material, e.g., during and/or after the printing. In some embodiments, humidity levels and/or oxygen levels in at least a portion of the enclosure (e.g., processing chamber, ancillary chamber, and/or build module) can be regulated such that an oxygenation and/or humidification of powder in the powder conveyance system is controlled. Oxygenation and/or humidification levels of recycled pretransformed material (e.g., recycled powder material) can be about 5 parts per million (ppm) to about 1500 ppm. The gas composition of the chamber can contain a level of oxygen that is at most about 4000 parts per million (ppm), 3000ppm, 2000 ppm, 1500ppm, OOppm, 500ppm, 400ppm, 100ppm, 50ppm, 10ppm, or 5ppm. The gas composition of the chamber can contain an oxygen level between any of the afore-mentioned values (e.g., from about 4000ppm to about 5ppm, from about 2000 ppm to about 500ppm, from about 1500ppm to about 500ppm, or from 500ppm to about 50ppm). Oxygenation and/or humidification levels of pre-transformed material can be about zero ppm. For example, oxygen content in pre-transformed material can be about 0 weight percent (wt %), 0.1 wt %, 0.25 wt %, 0.3 wt %, 0.5 wt %, 0.75 wt %, 1.0 wt %, or more. At times, atmospheric conditions can, in part, influence a flowability of pre-transformed material (e.g., powder material) from the layer dispensing mechanism. A dew point of an internal atmosphere of an enclosure (e.g., of the processing chamber) can be (I) below a level in which the powder particles absorb water such that they become reactive under condition of 3D printing process(es) and/or sufficient to cause measurable defects in a 3D object printed from the powder particles and (II) above a level of humidity below which the powder agglomerates, (e.g., electrostatically). In some embodiments, conditions (I) and/or (II) may depend in part on a type of powder material and/or on processing condition(s) of the 3D printing process(es). The gas composition of the chamber can contain a level of humidity that corresponds to a dew point of at most about -10 °C, -15 °C, -20 °C, -25 °C, -30 °C, -35 °C, -40 °C, -50 °C, -60 °C, or -70 °C. The gas composition of the chamber can contain a level of humidity that correspond to a dew point of between any of the aforementioned values, e.g., from about -70°C to abokilopascals60 °C to about -10 °C or from about -30 °C to about -20 °C. A dew point of an internal atmosphere of the enclosure (e.g., of the processing chamber) can be from about -80 °C to about -30 °C, from about -65 °C to about -40 °C, or from about -55 °C to about -45 °C, at an atmospheric pressure of at least about 10 kilo-Pascals (kPa), about 12 kPa, about 14 kPa, about 16 kPa, about 18 kPa, about 20 kPa above ambient pressure external to the enclosure. A dew point of an internal atmosphere of the enclosure can be any value within or including the afore-mentioned values. Examples of gas conveyance system and components (including control components), in-situ passivation systems, controlled oxidation methods and systems, 3D printing systems, control systems, software, and related processes, can be found in International Patent Applications Serial Nos. PCT/US17/60035 and PCT/US21/35350, each of which is incorporated herein by reference in its entirety.

[0193] In some embodiments, the one or more components of the layer dispensing mechanism are arranged in a specific configuration. The configuration may include coupling the one or more components to at least one shaft. The configuration may include translating the one or more components (e.g., by translating the shaft). The translation may be to the processing chamber from the ancillary chamber, or from the processing chamber to the ancillary chamber. The translation can be a lateral translation that is reversible, e.g., a back and forth translation. The layer dispensing mechanism may translate (e.g., laterally) along a trajectory, e.g. along a path. The translation may be along railings. The translation may be facilitated by a gear, an actuator, a belt, and/or a shaft. The trajectory may run (e.g., substantially) parallel to the target surface and/or platform. The trajectory may run from one side of the platform to the opposite side of the (i) platform and/or (ii) exposed surface of the material bed. The trajectory may run from one side of the material bed to an opposite side of the material bed. The layer dispenser may translate in a direction towards the processing chamber. The layer dispenser may translate, e.g., reversibly, in a direction towards or away from the ancillary chamber. One or more components of the layer dispensing mechanism may be (e.g., selectively, and/or controllably) operational during translation. The translation may be manually and/or automatically controlled, e.g., using any of the controllers disclosed herein. The configuration of the layer dispenser may comprise (i) a material dispensing mechanism, (ii) a material removal mechanism, (iii) or combination thereof. For example, the configuration may comprise placing (i) a material dispensing mechanism at a first position on a mount coupled to (e.g., followed by) (ii) a material removal mechanism. An example of a mount is provided in Fig. 15, 1501. At times, the configuration may include placing a material dispensing mechanism between the material removal mechanism and the material levelling mechanism. At times, the configuration may comprise placing (i) a material removal mechanism at the first position on the mount, coupled to (e.g., followed by) (ii) a material dispensing mechanism. The material dispensing and material removal may be performed synchronously (e.g., in the same translation cycle). Synchronously may be within a single translation cycle. A translation cycle may include translating the layer dispensing mechanism laterally from a first end of the material bed to a second end of the material bed. An end of a material bed may be a position on the periphery of the material bed. The material dispensing and material removal may be performed asynchronously. The material dispensing and material removal may be performed sequentially. For example, a first action (e.g., material dispensing) may be performed during a first portion of a translation cycle. The first portion of the translation cycle may be as the layer dispensing mechanism translates in a first direction, e.g., as the layer dispensing mechanism translates laterally from a first edge of the material bed to a second edge. The first edge and the second edge may be on opposing sides of a material bed. The first edge and the second edge may be located at (e.g., approximately) opposing points across a material bed having a circular cross section, e.g., where an axis through a center point of an exposed surface of the material bed intersects with a circumference of the exposed surface of material bed. A second action (e.g., material removal) may be performed during a second portion of the translation cycle. The second portion of the translation cycle may be as the layer dispensing mechanism translates in a second direction that is the opposite (e.g., reverse) direction of the first direction, e.g., as the layer mechanism translates laterally from the second end of the material bed to the first end of the material bed. The material dispensing and material removal operations may be performed simultaneously. For example, the first action (e.g., material dispensing) and the second action (e.g., material removal) may be performed during one portion of a translation cycle of the layer dispenser. The one portion of the translation cycle may be as the layer dispensing mechanism (e.g., mount thereof) translates in a direction, e.g., as the layer dispensing mechanism translates laterally from a first end of the material bed to its opposing second end. The material dispenser and material remover may be disposed on (e.g. connected to) the mount to facilitate dispensing the material followed by removal of portion of the dispensed material, e.g., when moving in the one direction. For example, when the material dispenser is mounted on the mount before the material remover, relative to the direction of translation of the layer dispensing mechanism (e.g., of its mount) in the direction.

[0194] At times, a (e.g., planar) layer of pre-transformed material may be dispensed during the translation cycle. The material bed may be formed by dispensing a plurality of (e.g., planar) layers of pre-transformed material. The operations o forming at least a portion of a material bed and generating the at least the portion of the material bed is used interchangeably herein. At times, the amount of pre-transformed material dispensed to form at least two (e.g., planar) layers of the material bed, may be constant. At times, the amount of pre-transformed material dispensed to form at least two (e.g., planar) layers of the material bed, may be different. For example, a first amount of pre-transformed material that is dispensed to form a first layer; and a second amount of pre-transformed material is dispensed to form a second layer. Occasionally, the first amount may be different from the second amount. Occasionally, the first amount may be (e.g., substantially) equal to the second amount. At times, the average height of at least two (e.g., planar) layers of pre-transformed material within the material bed may be (e.g., substantially) constant. At times, the average height of at least two (e.g., planar) layers of pretransformed material within the material bed may be different. For example, a first (e.g., planar) layer of pre-transformed material may have an average first height, and a second (e.g., planar) layer of pre-transformed material may have an average second height. At times, the second height may be different than the first height. At times, the second height may be (e.g., substantially) the same as the first height. In some instances, the amount of material dispensed to form a layer may vary across the layer. In some instances, the height of the layer may vary across the layer. In some instances, the amount of material dispensed to form a layer be (e.g., substantially) constant across the layer. In some instances, the height of the layer may be (e.g., substantially) constant across the layer. At times, a layer of material may be dispensed, and a portion thereof may be removed (e.g., by the material remover) during the translation cycle of the layer dispensing mechanism. For example, the layer of material may be dispensed during a first portion of the translation cycle and the portion of material may be removed during a second portion of the translation cycle. At times, a layer of material may be dispensed during a first translation cycle of the layer dispensing mechanism and a portion of the layer of material may be removed during a second translation cycle of the layer dispensing mechanism. At times, a single layer of material may be dispensed, and leveled (e.g., planarized) during the translation cycle in one direction. The translation cycle may comprise moving from one side of the material bed to its opposing side. The translation cycle may comprise moving from one side of the material bed to the opposing side, and back to the one side, e.g., and to the ancillary chamber. The material dispenser may be refilled with pre-transformed material (e.g., starting material such as powder) when at the ancillary chamber.

[0195] At times, a physical property of one or more components of the layer dispensing mechanism is controlled. The physical property may comprise velocity, speed, direction of movement, or acceleration. Controlling may include using at least one controller, e.g., as disclosed herein. Controlling may include modulation of the physical property (e.g., within a predetermined time frame). Controlling may include modulation of the physical property within a translation cycle of the layer dispensing mechanism. At times, one or more components (e.g., the material dispensing mechanism and/or the material removal mechanism) of the layer dispensing mechanism may be controlled to operate at a (e.g., substantially) constant velocity (e.g., throughout the translation cycle, throughout a material dispensing cycle, throughout a material leveling cycle and/or throughout a material removal cycle). At times, one or more components may be controlled to operate at a variable velocity. At times, one or more components may be controlled to operate at variable velocity within a portion of time of the translation cycle. At times, the velocity of one or more components of the layer dispensing mechanism, within a first time portion of the translation cycle and a second time portion of the translation cycle may be same. At times, the velocity of one or more components of the layer dispensing mechanism, within a first time portion of the translation cycle and a second time portion of the translation cycle may be different. At times, within the translation cycle, the velocity of one or more components of the layer dispensing mechanism at a first position may be different than the velocity of the one or more components at a second position. At times, within the translation cycle, the velocity of one or more components of the layer dispensing mechanism at a first position may be the same as the velocity of the one or more components at a second position. At times, a component of the layer dispensing mechanism may be individually controlled. At times, at least two or more components of the layer dispensing mechanism may be collectively controlled. At times, at least two components of the layer dispensing mechanism may be controlled by the same controller. At times, at least two components of the layer dispensing mechanism may be controlled by a different controller.

[0196] In some examples, the layer dispensing mechanism comprises at least one material dispensing mechanism and at least one planarizing mechanism (e.g., a material remover). The at least one material dispensing mechanism and at least one planarizing mechanism may be connected or disconnected. The material dispensing mechanism can operate in concert with the planarizing mechanism (e.g., a vacuum suction) and/or independently with the planarizing mechanism. At times, the material dispensing mechanism may proceed before the material removal mechanism, as they progress along the material bed. The material dispensing mechanism or any part thereof (e.g., its internal reservoir) may vibrate. The vibrations may be induced by one or more agitators. The material dispensing mechanism, or any component thereof, may vibrate, e.g., without substantially vibrating the planarizing mechanisms. The material dispensing mechanism, or any component thereof, may vibrate without (e.g., substantially) vibrating the material removal mechanism. At times, the layer dispensing mechanism comprises a material dispensing mechanism and a planarizing mechanism and is devoid of a blade (e.g., devoid of a shearing blade).

[0197] At times, an agitator is coupled to a body of the material dispensing mechanism. The agitator may be mechanically and/or sonically agitated. The agitator may be isolated from the body of the material dispenser. A transducer of the agitator may be disposed outside of a processing chamber enclosing the target surface towards which the material dispenser dispenses the starting material (e.g., the powder). The transducer of the agitator may be disposed in the processing chamber enclosing the target surface. The material dispenser may include an agitator operatively coupled to (e.g., physically coupled to) a panel of the material dispenser. The panel may comprise a slab, board, beam, plank, or a leaf. The panel may be a thin walled structure. The panel may comprise two opposing parallel exposed surfaces. For example, a vertical cross section of the panel may be non-tapered, e.g., be rectangular. The panel may comprise two opposing non-parallel exposed surfaces. For example, a vertical cross section of the panel may be tapered. The panel may be disposed adjacent to an exit port of the dispenser, e.g., from which the starting material (e.g., pre-transformed material) is being dispensed to the target surface. The panel may be thin. The panel may be configured to act as a conduit (e.g., duct) for the agitation, e.g., vibration. The panel may act as an acoustic duct. A FLS of a surface of the panel may be larger than a FLS of a thickness of the panel. Fig. 13 shows an example of a vertical cross section of panel 1351 in which opposing sides 1352a and 1352b are parallel to each other and are planar. Panel 1351 has one thickness 1353a that is equal to 1353b. Fig. 13 shows an example of a vertical cross section of panel 1361 in which opposing sides 1362a and 1362b are non-parallel to each other - are tapered, which each of opposing sides 1363a and 1362b is planar. In the example of panel 1361 , the thickness of panel 1361 differs as is illustrated by thickness 1363b being larger than thickness 1363a. Fig. 13 shows an example of a vertical cross section of panel 1371 in which opposing sides 1372a and 1372b are parallel to each other and are curved. Panel 1371 has one thickness 1373a that is equal to 1373b. Fig. 13 shows an example of a vertical cross section of panel 1381 in which opposing sides 1382a and 1382b are non-parallel to each other - are tapered, which each of opposing sides 1383a and 1382b is curved. In the example of panel 1381 , the thickness of panel 1381 differs as is illustrated by thickness 1383b being larger than thickness 1383a. Panels 1351 , 1361 , 1371 , and 1381 are shown in relation to Cartesian coordinate system 1390. The panel may comprise a gate, e.g., the panel may constitute a gate. The gate may be of the exit port of the material dispenser. The agitator may facilitate increasing a fluidity of the powder material to facilitate its egress (e.g., exit) from the dispenser. For example, the agitator may physically connect to the panel, cause the panel to vibrate, which vibration will cause powder particles adjacent to the panel to vibrate, thus increasing their flowability to flow out of an exit port of the dispenser adjacent to the panel. The agitator may be part of, or constitute, the panel. For example, the panel may operate as a waveguide. The body of the material dispenser may include, or be operatively coupled to, the panel. An agitator may vibrate at a frequency of at least about 10 Kilohertz (kHz), 15 kHz, 20 kHz, 30 kHz, 40 kHz, or 50 kHz. The agitator may vibrate at a frequency from about 10 Kilohertz (kHz) to about 50 kHz, from about 25 kHz to about 40 kHz, or from about 15 kHz to about 50 kHz. A vibrational frequency of the agitator may be selected, for example, based at least in part on at least one characteristic of the powder material comprising average particle size, average size distribution, deviation from a spherical shape of the powder particles, material type of the powder, surface roughness of the particles, or the like.

[0198] The distance between the functionalities of the various components of the layer dispensing mechanism is referred to herein as the “distance-between-functionalities.” The distance-between-functionalities can be at least about 100 m, 150 pm, 200 pm, 300 pm, 400 pm, 500 pm, 600 pm, 700 pm, 800 pm, 900 pm, 1000 pm, 2 millimeters (mm), 3 mm, or 5 mm. The distance-between-functionalities can be at most about 5 mm, 3 mm, 2 mm, 1000 pm, 900 pm, 800 pm, 700 pm, 60 pm, 500 pm, 450 pm, 400 pm, 350 pm, 300 pm, 250 pm, 200 pm, or 150 pm. The distance-between-functionalities can be of any value between the afore-mentioned values (e.g., from about 100 pm to about 1000 pm, 100 pm to about 500 pm, 300 pm to about 600 pm, 500 pm to about 5 mm). In some examples, the distance between the exit port of the material dispensing mechanism (or of the material fall) and the entrance port (e.g., nozzle) of the material removal mechanism is equal to the distance-of-functionalities. The various functionalities of the layer dispenser may be operatively coupled to a mount, e.g., physically connected to the mount.

[0199] In some embodiments, the layer dispensing mechanism is separated from the target surface by a gap. The target surface may comprise a build plate, or an exposed surface of a material bed. The gap may be maintained during operation of the layer dispenser. The gap may be at least about 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 5 mm, 10 mm, or 20 mm. The gap can be any value between the afore-mentioned values, e.g., from about 1 mm to about 2 mm, from about 1.5 mm to about 2.5 mm, from about 0.75 mm to about 2.25 mm, from about 0.5 mm to about 20 mm. At times, a distance between layer dispensing mechanism (e.g., components of the layer dispensing mechanism) and a top surface of a 3D object protruding from an exposed surface of the material bed can be at least about 0.5 mm, 1 mm, 1.5 mm, 2 mm, or 2.5 mm. The distance between the top surface of a 3D object protruding from an exposed surface of the material bed can be any value between the afore-mentioned values, e.g., from about 1 mm to about 2 mm, from about 1 .5 mm to about 2.5 mm, from about 0.75 mm to about 2.25 mm. The distance between the top surface of a 3D object protruding from the exposed surface of the material can be at most about the value of the gap between the target surface and the layer dispensing mechanism, e.g., the closest component of the layer dispensing mechanism to the target surface. In some embodiments, a component of the layer dispensing mechanism that is closest to a top surface of a 3D object protruding from the exposed surface of the material bed is a planarizing mechanism, e.g., a vacuum nozzle of a planarizing mechanism. A closest distance between a target surface and the layer dispensing mechanism may be larger than a thickness (e.g., height) of the dispensed layer of pre-transformed material, e.g., larger by at least about 50%, 100%, 200%, 500%, 800%, 1000% or larger. Larger may be between any of the aforementioned values (e.g., from about 50% to about 1000%).

[0200] At times, a central tendency of thickness of a dispensed layer of pre-transformed material (e.g., powder material) on an exposed surface is smaller than a height of protrusion of a 3D object above the exposed surface of the material bed. For example, at least about 0.1 millimeters (mm), 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.75 mm, 1.0 mm, 1.25 mm, 1.5 mm, 2.0 mm, or more of the 3D object protruding above the exposed surface of the material bed is above a top surface of the dispensed layer of pre-transformed material on the exposed surface of the material bed. For example, a height of the 3D object protruding above the top surface of the dispensed layer of pre-transformed material on the exposed surface of the material bed can range between any of the afore-mentioned values, for example, from about 20 microns (pm) to about 0.75 mm, from about 0.5 mm to about 1 .0 mm, from about 1 .0 mm to about 2.0 mm, or from about 0.3 mm to about 1 .5 mm. At times, a height of protrusion of the 3D object above the exposed surface of the material bed may be at least about 0%, 2%, 10%, 50%, 100%, 200%, 400%, 500% or greater than the central tendency of thickness (e.g., height) of the dispensed layer. The height can be along the gravitational vector pointing to the gravitational center. The height can be a vertical height. The height of protrusion of the 3D object above the exposed surface of the material bed can be any value between the afore-mentioned values, e.g., from about 0% to about 500%, from about 100% to about 400%, or from about 2% to about 50%, than the central tendency of thickness of the dispensed layer. A height (e.g., a vertical height) of the protrusion above a target surface may be determined, for example, utilizing various optical sensors, optical detectors, and the like, to construct a height map of at least a portion of the target surface that may include one or more protrusions of 3D objects. Examples of height mapping processes and systems, optical sensors, optical detectors, 3D printing systems, apparatuses, devices, and any of their components, and 3D printing processes can be found in International Patent Application Serial No. PCT/US17/18191 filed February 16, 2017, and U.S. Patent Application 15/435,078 filed February 16, 2017, each of which is incorporated herein by reference in their entirety.

[0201] At times, the layer dispensing mechanism comprises a material dispenser and a material remover. The material remover (e.g., a nozzle) may be coupled to an attractive source, e.g., a vacuum source. The material dispenser may dispense pre-transformed material on an exposed surface of a material bed to form a first layer having a first central tendency of planarity and a second central tendency of thickness. For example, a first layer can have a first central tendency of planarity (e.g., a peak-to-valley variation distance, an Rvalue, or a /?_zvalue) of about 20 microns (pm), 22 pm, 24 pm, 28 pm, 30 pm, 50 pm, or 75 pm. For example, the first layer can have a first central tendency of planarity that can range between any of the aforementioned values, e.g., from about 20 microns (pm) to about 30 pm, from about 22 pm to about 50 pm, or from about 28 pm to about 75 pm. For example, a first layer can have a first central tendency of planarity (e.g., a percentage deviation) of about 15%, 35 %, about 40 %, about 45%, about 50%, or about 65%. For example, a first layer can have a second central tendency of thickness of about 30 microns (pm), 40 pm, 50 pm, 75 pm, 85 pm, 100 pm, 125 pm, 150 pm, 175 pm, 200 pm, or 250 pm. For example, the first layer can have a second central tendency of thickness that can range between any of the afore-mentioned values, e.g., from about 30 pm to about 75 pm, from about 50 pm to about 150 pm, or from about 75 pm to about 250 pm. The material remover may remove a portion of the first layer to form a second layer having a third central tendency of planarity and a fourth central tendency of thickness. For example, a third central tendency of planarity of the second layer can be at most about 50 microns (pm), about 40 pm, about 30 pm, about 25 pm, about 20 pm, 10 pm, 5 pm, or less. For example, the third central tendency of planarity of the second layer can range between any of the afore-mentioned values, e.g., from about 5 pm to about 30 pm, from about 10 pm to about 40 pm, or from about 20 pm to about 50 pm. For example, a fourth central tendency of thickness for the second layer can be about 10 pm, 15 pm, 20 pm, 25 pm, 35 pm, 50 pm, or 100 pm. For example, the fourth central tendency of thickness of the second layer can range between any of the afore-mentioned values, e.g., from about 10 pm to about 35 pm, from about 20 pm to about 50 pm, from 25 pm to about 50 pm, or from about 10 pm to about 100 pm.

[0202] At times, the layer dispensing mechanism comprises a material remover configured to remove a portion of the pre-transformed material from the material bed. The force exerted by the force source through the material removal mechanism may cause at least a portion of the pretransformed material (e.g., powder particles) to lift (e.g., become airborne) from the material bed, and travel (e.g., influx, and ingress) towards the entrance port of the material removal mechanism (e.g., nozzle entrance). The lifted pre-transformed material (or at times, unwanted transformed material and/or debris) may travel (e.g., flow) within the material removal mechanism, e.g., within the internal compartment and/or within the nozzle. The influx may comprise laminar, turbulent, and/or curved movement of the lifted pre-transformed material. The influx may be towards the reservoir. The influx may be towards the force source. The gap between the exposed surface of the material bed and the entrance port of the material removal mechanism (e.g., nozzle entrance) may depend on the at least one characteristic of the pretransformed material (e.g., powder material), e.g., as disclosed herein. For example, on average FLS and/or mass of the pre-transformed material sections (e.g., particulate material). For example, on the mean FLS and/or mass of the particulate material. In some embodiments, the structure of the internal compartment and/or nozzle enables uniform removal of pre-transformed material from the material bed. In some examples, the amount of force generated by the force source and/or its distribution through the internal compartment and/or nozzle of the material removal mechanism enables uniform removal of pre-transformed material from the material bed. For example, the structure of the internal compartment and/or nozzle of the remover enables uniform suction of pre-transformed material from the material bed. The structure of the internal compartment and/or nozzle of the remover may influence the velocity of the influx of pretransformed material (e.g., unused material) into the material removal mechanism. The amount of force generated by the force source and/or its distribution through the internal compartment and/or nozzle of the material removal mechanism may influence the homogeneity of the influx velocity along the entrance port(s) and/or along the material bed.

[0203] The material removal mechanism may remove at least a portion (e.g., the entire) of at least the exposed surface of the material bed. The at least a portion may be at a designated location (e.g., controlled manually or by the controller). For example, the material removal mechanism may form depressions (e.g., voids) in a material bed comprising a first pretransformed material, which depressions may be subsequently filed with a layer or sub-layer of a second pre-transformed material. The second pre-transformed material may be substantially identical, or different from the first pre-transformed material. The sub layer may be smaller from a layer with respect to their height and/or horizontal cross section.

[0204] In some embodiments, the layer dispenser is utilized in a 3D printing, e.g., to form a material bed utilized to form a 3D object. The layer dispensing mechanism (e.g., material removal mechanism) may facilitate the formation of a 3D object that has a locally different microstructure. The locally different microstructure can be between different layers, or within a given layer. For example, at least one portion of a layer within the 3D object may differ from another portion within that same layer, in terms of its microstructure. The microstructure difference may be any difference recited above.

[0205] In some embodiments, the layer dispensing mechanism comprises a material dispenser. Fig. 13 shows a side view example of layer dispensing mechanisms comprising a material dispensing mechanism 1311 attached to a planarizing mechanism, e.g., a material removal mechanism 1313. Fig. 13 shows an example of a layer dispensing mechanism comprising: a material dispensing mechanism 1311 which is connected to a material removal mechanism 1313; which layer dispensing mechanism is disposed above the material bed 1315. The layer dispensing mechanism and material bed in Fig. 13 are disposed in relation to gravitational vector 1399 directed towards gravitational center G.

[0206] In some embodiments, the layer dispenser comprises a material remover. The layer dispensing mechanism may comprise a material (e.g., powder) removal mechanism (e.g., 1313) that comprises one or more openings. The one or more openings may be included in a nozzle. The nozzle may comprise an adjustable opening (e.g., controlled by a controller). The height of the nozzle opening relative to the exposed surface of the material bed may be adjustable (e.g., controlled by a controller). The material removal mechanism may comprise a reservoir in which the material may at least temporarily accumulate. The evacuated material may comprise a pretransformed material that is evacuated by the material removal mechanism. The evacuated material may comprise a transformed material that did not form the 3D object and/or debris. The debris may be generated during the 3D printing process. The nozzle may comprise an adjustable opening (e.g., controlled by a controller). The height of the nozzle opening relative to the target surface of the material bed may be adjustable (e.g., controlled by a controller). The material removal mechanism may comprise a reservoir in which the material (that is evacuated by the material removal mechanism) may at least temporarily accumulate. Control may include regulate and/or direct. The adjustment may comprise manual and/or automatic adjustment (e.g., using the controller(s), such as any controller disclosed herein). The FLS of the entrance port (e.g., cross section thereof) of the material removal mechanism (e.g., nozzle diameter) may be at least about 0.1 mm, 0.4 mm, 0.7 mm, 0.9 mm, 1.1 mm, 1.3 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 5 mm, 7 mm, or 10 mm. The FLS of the entrance port of the material removal mechanism (e.g., nozzle diameter) may be at most about 0.1mm, 0.4 mm, 0.7 mm, 0.9 mm, 1.1 mm, 1.3 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 5 mm, 7 mm, or 10 mm. The FLS of the entrance port of the material removal mechanism (e.g., nozzle diameter) may be of any value between the afore-mentioned values (e.g., from about 0.1 mm to about 7mm, from about 0.1mm to about 0.6mm, from about 0.6mm to about 0.9mm, from about 0.9mm to about 3mm, or from about 3mm to about 10mm).

[0207] In some embodiments, the nozzle is separated from the exposed surface of the material bed by a gap. The nozzle may comprise a nozzle of the material remover or a nozzle of the material dispenser. The gap may comprise a gas. The gap may be an atmospheric gap. The extent of the gap and/or the FLS of the entrance port (e.g., diameter) of the nozzle may be changeable (e.g., before, after, and/or during the 3D printing). For example, that change in the nozzle opening port may occur during the operation of the material removal mechanism. For example, that change may occur before the initiation of the 3D printing. For example, that change may occur during the formation of the 3D object. For example, that change may occur during the formation of a layer of hardened material. For example, that change may occur after transforming a portion of a layer of pre-transformed (e.g., powder) material. For example, that change may occur before deposition a subsequent layer of pre-transformed material. For example, that change may occur during the progression of the layer dispensing mechanism (e.g., of which the material removal mechanism is a part of) along the exposed surface of the material bed. The progression may be parallel to the exposed surface of the material bed. The progression may be a lateral progression (e.g., from one side of the material bed to the opposite side of the material bed). In some embodiments, the extent of the gap and/or the FLS of the entrance port (e.g., diameter) of the nozzle may be unchanged before, after, and /or during the formation of: the 3D object, layer of hardened material, transformed material, or any combination thereof. The extent of the gap and/or the FLS of the entrance port (e.g., diameter) of the nozzle may be unchanged during the formation of: the 3D object, layer of hardened material, transformed material, or any combination thereof. The vertical distance of the gap from the exposed surface of the target surface to the entrance port of the nozzle (e.g., 3312) may be at least about 0.05mm, 0.1 mm, 0.25mm, 0.5mm, 1 mm, 2mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm. The vertical distance of the gap from the exposed surface of the powder bed may be at most about 0.05mm, 0.1 mm, 0.25mm, 0.5mm, 1 mm, 2mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or 20 mm. The vertical distance of the gap from the exposed surface of the powder bed may be any value between the afore-mentioned values (e.g., from about 0.05mm to about 20mm, from about 0.05mm to about 0.5mm, from about 0.2mm to about 3mm, from about 0.1mm to about 10mm, or from about 3mm to about 20mm).

[0208] At times, a temperature of the material attracted by the recoater from the material bed changes during a material removal operation, e.g., as the material removal mechanism translates along the material bed and removes excess of material (e.g., powder) to facilitate a (e.g., substantially) planar exposed surface of the material bed, e.g., for usage in a 3D printing process. At times, various portions of the exposed surface of a material bed have different temperatures. The material attracted, or to be attracted, by the material removal mechanism may be susceptible to temperature changes. The material attracted, or to be attracted, by the material removal mechanism may be susceptible to a level of humidity. For example, the material may exhibit tacky properties that are temperature and/or humidity dependent. The tacky properties may comprise the material clamping up, or aggregating. For example, when the material comprises particulate matter (e.g., powder), the powder may aggregate at certain temperature and/or humidity conditions, for example, high temperature and/or low humidity. Without wishing to be bound to theory, the aggregation in low humidity conditions may be due to static electricity. At times, using the same attractive force causes various amounts of material (of the same type) to be attracted (e.g., vacuumed) by the material removal mechanism. Without wishing to be bound to theory, this may be due to temperature dependency of tackiness (e.g., agglomeration and/or adhesion) of the material. For example, there may be a tendency to attract (e.g., vacuum) a different amount of material (e.g., powder) over hotter portion of the material bed as compared to over a cooler portion of the material bed, while using the same degree of attractive force. The different amount may be larger or smaller. Examples of nozzles, material removal mechanism, layer dispensers, material dispensers, flows above the material bed, 3D printing systems, 3D printing processes, control systems, and software can be found in U.S. patent application serial number 17/731 ,447 and international patent application serial number PCT/US16/66000, each of which is incorporated herein by reference in its entirety.

[0209] Fig. 14 schematically depict bottom views of various mechanisms for removing the pretransformed material as part of the material removal mechanism. Example 1400 schematically depicts a bottom view of a material removal mechanism having an elongated material entrance port 1412 and an internal compartment (e.g., cavity) having a triangular horizontal cross section 1411 of the body of the material removal mechanism. Example 1460 schematically depicts a bottom view of a material removal mechanism body 1461 having an elongated material entrance opening port 1462, the material removal mechanism being connected 1465 with channel 1464 through which the pre-transformed material leaves the material removal mechanism. The nozzle may be a long nozzle (e.g., vacuum nozzle) in the horizontal direction, e.g., having an elongated horizontal opening. The long nozzle may be referred herein as an elongated nozzle. Example 1460 shows an example of an elongated nozzle in the horizontal direction, having a horizontally elongated material entry port 1462, the material remover being coupled to a channel 1464 (hose) through coupler 1465, e.g., connector. The channel may be connected to an attractive force (e.g., vacuum). In some examples, the nozzle spans at least a portion of the width or length of the material bed. In some examples, the nozzle spans less than the width or length of the material bed. The nozzle may be symmetric or asymmetric. The symmetry axis may be horizontal and/or vertical (e.g., (e.g., substantially) parallel to the platform). A cross section of the material removal member entrance port (e.g., nozzle entrance opening) may be rectangular (e.g., 1462) or elliptical. A cross section of the material removal member opening port (e.g., nozzle entrance) may comprise a curvature (e.g., curved edge) or a straight line (e.g., straight edge). The FLS (e.g., width to length) of the opening port cross section may have an aspect ratio of at least 1 :2, 1 :10, 1 :100, 1 :1000, 1 :1000, or 1 :10000. The material removal member may comprise a connector. The connector may be to a power source, e.g., an attractive power source. The connector may be to a reservoir. The connector may be to a reservoir and to the power source. The channel may be connected to an attractive force, e.g., vacuum. The power source may be a source of gas flow (e.g., compressed gas, or vacuum), electrostatic force, and/or magnetic force. The connector may facilitate fluid connection, e.g., such that the pretransformed material may flow through the channel. The connector may allow pre-transformed material, debris to flow through the channel and towards the attractive force source. The connector may allow gas to flow through. The connector may comprise connection to a channel (e.g., 1464). The channel (e.g., tube) may be flexible or non-flexible. Examples of connectors are shown in 1465 and 1415. Examples of channels are shown in 1414 and 1464. In some examples, the material removal member comprises an internal compartment. The internal compartment may be a pre-transformed material collection compartment. For example, the internal compartment may be a powder collection compartment, or a liquid collection compartment. The internal compartment may connect (e.g., fluidly connect) to the power source (e.g., through the connector and the channel). The internal compartment may comprise the connector. Fig. 14, 1460 shows an example of a connector 1465. The internal compartment may connect (e.g., fluidly) to the one or more nozzles. The internal compartment may connect (e.g., fluidly) to the one or more nozzles and to the power source and/or reservoir. The internal compartment may be symmetric or asymmetric. The symmetry or asymmetry may be in the horizontal and/or vertical direction. The internal compartment may comprise the shape of a cylinder, cone, box, ellipsoid, egg, or a spiral. The cross section (e.g., horizontal and/or vertical) may comprise the shape of a triangle (e.g., 1411 , and 1451), ellipse, rectangle (e.g., 1461), parallelogram, trapezoid, egg cross section, spiral cross section, star, sickle, or crescent. The cross section (e.g., horizontal and/or vertical) may comprise a concave shape or a convex shape. During operation, the long axis of the internal compartment may be (e.g., substantially) parallel to the platform. During operation, the long axis of the internal compartment may be disposed at an angle relative to the platform. The angle may be at most about 50°, 40°, 30°, 20°, 10°, or 5°. The angle may be between any of the aforementioned angles. The angle may be configured to allow expansion of the cavity to facilitate homogenous attraction of the pretransformed material from the material bed into the nozzle. During operation, a short axis of the internal compartment may be (e.g., substantially) perpendicular to the platform. The internal compartment may comprise a curvature. The internal compartment may comprise a curved plane. The internal compartment may comprise a planar (e.g., non-curved, or flat) plane. A horizontal cross section of the internal compartment may be symmetric (e.g., a rectangle) or asymmetric (e.g., a triangle). The internal compartment may be wider (e.g., 1416) towards the connector (e.g., 1415). The internal compartment may be narrower (e.g., 1413) away from the connector. The shape of the internal compartment may allow substantial uniform removal (e.g., suction) of the pre-transformed material by the nozzle(s) of the material removal member along its horizontal span. The internal shape of the internal compartment may narrow towards a distant position from the connector. The narrowing may be gradual or non-gradual. The narrowing may be linear, logarithmic, or exponential. The internal compartment of the material removal member may have a shape that allows movement of the pre-transformed material within the compartment. The movement of the pre-transformed material within the compartment may comprise laminar or curved movement. The curved movement may comprise a spiraling movement. The curved movement may comprise a helical movement. The internal compartment may have an internal shape of a helix, spiral, or screw. The screw may be a narrowing screw, a cylindrical screw, or any combination thereof (e.g., a household type screw, or an Archimedean screw). Viewed from below, the opening port of the nozzle may horizontally overlap the internal compartment (e.g., centered below as shown for example in Fig. 14, 1460), or not overlap. In some embodiments, the opening port of the nozzle is horizontally separated from the internal compartment by a gap. The power source, reservoir, and/or internal compartment may be stationary or translational with respect to the material bed. The material removal mechanism (or any of its components) may translate relative to the material bed. For example, the material removal mechanism may be stationary, and the material bed may be translating. For example, the material removal mechanism may translate, and the material bed may be stationary. For example, both the material removal mechanism and the material bed may be translating (e.g., in the same direction, in opposite directions and/or at different speeds).

[0210] Fig. 14 shows in example 1450 a schematic vertical cross section of a material remover having an internal compartment (e.g., cavity) having a triangular vertical cross section 1451 of the body of the material removal mechanism, an entrance port 1452, a coupler 1455, and a channel 1454. Body 1451 has an internal compartment (e.g., cavity) having a long axis 1457 that is tilted by angle alpha (a) relative to the entrance opening that is horizontal, e.g., during operation.

[0211] In some embodiments, the material removal mechanism comprises an elongated material entrance channel, and an internal compartment having a tapered internal cavity, e.g., having diminished volume along the elongated material entrance port. The material removal mechanism may be configured to attract (e.g., vacuum) a remainder of material (e.g., powder) dispensed to form a material bed. The material removal mechanism may be mounted to a mount. The mount may comprise triangular supports. The material removal mechanism may be a part of a layer dispensing mechanism (e.g., a recoater). The cavity may have an exit opening (e.g., exit port) (e.g., a hole) through which attracted material exits the cavity. The exit port) may be on a side of the cavity, or along the long axis of the cavity. The cavity may have a long axis having a first end and an opposing second end. The exit port may be close, or at, the first end of the cavity. The tapered cavity can be linearly or non-linearly tapered. The tapered cavity can be evenly or non-evenly tapered. In some embodiments, the material removal mechanism is configured to ease of manufacture, assembly, and/or functional optimization. The material removal mechanism may be formed from one integral portion, two integral portion, three integral portion, or more integral portion. Each integral portion may be a single piece of material (e.g., comprising elemental metal, metal alloy, ceramic, or an allotrope of elemental carbon). The integral piece may be molded, machined, or 3D printed. The integral portion may facilitate one or more functionalities of the material removal mechanism. For example, the integral portion may comprise a portion of an internal cavity and a portion of a nozzle. For example, the integral portion may comprise a portion of an internal cavity, a portion of a nozzle, and at least a portion of a mounting piece (e.g., a mount). A sealant may be disposed in at least one of the integral portions to facilitate tight connection and/or hinder spillage of material attracted through the material removal mechanism (e.g., through the nozzle, cavity, and material exit port). The seal may comprise a flexible material. The seal may comprise a solid-to-solid tight seal. At least two of the portions of the material removal mechanism may be coupled using one or more fasteners (e.g., screws or clips).

[0212] Fig. 14 shows in a vertical cross-sectional example and internal view of a material removal mechanism 1420 having a nozzle looking into cavity 1423 to its far second side. In the example shown material removal mechanism 1420, two side 1421 and 1422 of the nozzle of the material removal system form a material entrance channel ending in tip 1424 that includes the entrance port, which material entrance channel has a straight vertical cross section (e.g., is devoid of a curvature or an angle). Side 1421 is a tailing edge of the nozzle, and 1422 is a leading edge of the nozzle, with respect to the direction of movement 1429 of the material removal mechanism.

[0213] Fig. 14 shows a perspective and vertical cross-sectional example of a material removal mechanism 1430 including a nozzle having a first side 1431 and a second side 1432. The material removal mechanism has a cavity 1433 configured to accommodate any material (e.g., powder) attracted to the cavity through the nozzle opening ending at tip 1434a, nozzle opening extends along the tip of the material removal mechanism, e.g., from 1434a towards the opposing end, including position 1434b. Cavity 1433 has an exit port (e.g., exit opening) 1435 through which attracted material (e.g., from a material bed) is removed from cavity 1433. Opening 1435 can be operatively coupled (e.g., using a channel such as a hose) to a force generator (e.g., a vacuum pump, a magnetic force, or an electrostatic force generator). In the example shown in material removal mechanism 1430, two side 1431 and 1432 of the nozzle of the material removal system form a material entrance channel ending in tip 1434a-1434b, which material entrance channel has a bent vertical cross section. The material removal mechanism in example 1430 shows the mount portion 1437 above one nozzle portion 1431. In the example of Fig. 14, portion 1431 of the mount and portion (e.g., half nozzle) 1432 of the nozzle form one integral piece. Examples of material removal mechanism, layer dispensers, material dispensers, flows above the material bed, 3D printing systems, 3D printing processes, control systems, and software can be found in International Patent Application Serial No. PCT/US15/36802 which are fully incorporated herein by reference in its entirety. Material removal mechanism 1420 depicts another view of material removal mechanism similar to material removal mechanism 1420. In material removal mechanism 1430 the nozzle 1434a has a bent channel, and in material removal mechanism 1420, the nozzle has a straight channel. Material removal mechanisms 1430 and 1420 are disposed in relation to gravitational vector 1499 directed towards gravitational center G.

[0214] Fig. 14 shows in example 1470 a vertical cross-sectional example of a of nozzle of the material removal mechanism looking into cavity 1472 to its far second side, disposed with respect to gravitational vector 1499 pointing towards the environmental gravitational center. In the example shown in 1470, two sides of the nozzle - a first side 1475 and a second side 1476 - form a material entrance opening channel extending from internal cavity 1472 to tip 1477. The channel in example 1470 has a straight vertical cross section (e.g., is devoid of a curvature or an angle), and is overall (e.g., substantially) normal to the first/second exposed surface and slightly expands from the tip to the internal cavity, e.g., symmetrically along its long axis (e.g., to form a triangular vertical cross section). Side 1476 can be a tailing side of the nozzle, and side 1475 can be a leading side of the nozzle, e.g., with respect to the direction of movement 1471 of the material removal mechanism such as during the removal operation. Side 1476 is curved at its bottom most tip, whereas side 1475 has a (e.g., substantially) flat bottom side facing the first/second exposed surface of material bed 1480. The material removal mechanism is configured to attract material from a first exposed surface 1474 of material bed 1480 to generate a second exposed surface 1473 as it translates laterally along the exposed surface in direction 1471 , e.g., when the material removal mechanism is connected to an operating attractive force source. Tip 1477 of the nozzle is disposed at a gap 1489 distanced from the first exposed surface 1474. The first side 1475 has a first external surface 1478 facing the first/second exposed surface of material bed 1480, which first external surface 1478 is of the flat bottom side. The first surface 1478 is disposed (e.g., substantially) parallel with the first/second exposed surface of material bed 1480. The second side 1476 has a second external surface 1481 facing the first/second exposed surface of material bed 1480, which second external exposed surface 1481 that forms an angle beta (B) with the first/second exposed surface of material bed 1480. An optional O-ring may be disposed in location 1479 representing an optional O-ring groove. In the example shown in 1470, first external surface 1478 has (i) a smaller vertical cross section and (ii) occupies a smaller area, as those of the second external surface 1481 respectively. The two opposing sides 1476 and 1475 are asymmetric, e.g., with respect to the channel, with respect to the direction of suction of the material from the exposed surface into the internal compartment of the nozzle during operation of the nozzle, and/or with respect to gravitational vector 1499. A slope is formed between the first exposed surface 1474 and the second exposed surface 1473, having lateral length 1485.

[0215] Fig. 15 depicts in 1500 a perspective vertical cross-sectional view of a cavity 1502 of a material removal mechanism, which cavity 1502 is tapered towards a first end 1504. The cavity has a second opposing end 1508 and an exit port 1503 close to the second opposing end. Exit port 1503 is disposed along a long axis of the cavity. The material removal mechanism having cavity 1502, is mounted to mount 1501 using fasteners (screws) such as 1505. The mount comprises supporting beams such as 1506 arranged as sides of triangles forming triangular open spaces such as 1507. Fig. 15 depicts in 1550 a side vertical cross-sectional view of cavity 1502 showing exit port 1503 and first end 1504 of tapered cavity 1502 having long axis 1555. In some embodiments, the mount is part of, or is operatively coupled to, at least one portion of the cavity of the material removal mechanism. In some embodiments, the material removal mechanism comprises three portions: a mount, a first half of a cavity and nozzle portion, and a second half of a cavity and nozzle portion. Fig. 15 shown in 1500 and in 1500 a mount coupled with fasteners (e.g., screws) to one half of the cavity and nozzle portion. In some embodiments, half of the cavity and half of the nozzle form one integral piece. The two halves of the integrated half-cavity and half-nozzle can be coupled together using fasteners (e.g., screws such as 1509). A sealant (e.g., flexible material) is disposed at one of the halves of the integral half-cavity and half-nozzle, e.g., to hinder any leakage of material attracted through the cavity. Fig. 15 shows an example of a sealant in 1558. The material removal mechanisms in examples 1500 and 1550 are depicted in relation to gravitational vector 1599 directed towards gravitational center G. [0216] In some configurations, the 3D printer comprises a bulk reservoir (e.g., a tank, a pool, a tub, hopper, or a basin). The bulk reservoir may comprise pre-transformed material, e.g., starting material for a 3D printing process. The bulk reservoir may comprise a mechanism configured to deliver the pre-transformed material from the bulk reservoir to at least one component (e.g., material dispenser) of the layer dispensing mechanism. The bulk reservoir can be connected or disconnected from the layer dispensing mechanism (e.g., from the material dispenser). The disconnected pre-transformed material dispenser can be located above, below or to the side of the material bed. The disconnected pre-transformed material dispenser can be located above the material bed, for example above the material exit port to the material dispenser within the layer dispensing mechanism. Above may be in a position away from the gravitational center. The bulk reservoir may be connected to the material dispensing mechanism (e.g., layer dispenser) that can be a component of (or be coupled to) the layer dispensing mechanism. The bulk reservoir may be located above, below or to the side of the layer dispensing mechanism. The layer dispensing mechanism and/or the bulk reservoir have at least one opening port (e.g., for the pre-transformed material to move to and/or from). Pretransformed material can be stored in the bulk reservoir. The bulk reservoir may hold at least an amount of material sufficient for one layer, several layers, or sufficient to build the entire 3D object. The bulk reservoir may hold at least about 200 grams (gr), 400gr, 500gr, 600gr, 800gr, 1 Kilogram (Kg), or 1.5Kg of pre-transformed material. The bulk reservoir may hold at most 200 gr, 400gr, 500gr, 600gr, 800gr, 1 Kg, or 1.5Kg of pre-transformed material. The bulk reservoir may hold an amount of material between any of the afore-mentioned amounts of bulk reservoir material (e.g., from about 200grto about 1.5Kg, from about 200 grto about 800gr, or from about 700gr to about 1 .5 kg). Material from the bulk reservoir can travel to the layer dispensing mechanism via a force. The force can be natural (e.g., gravity), or artificial (e.g., using an actuator such as, for example, a pump). The force may comprise friction. Examples of 3D printing systems and their components (e.g., bulk reservoir), 3D printing processes, 3D objects, control systems, and software can be found in International Patent Application Serial Number PCT/US15/36802 that is incorporated herein by reference in its entirety.

[0217] In some embodiments, the pre-transformed material dispenser reservoir resides within the material dispensing mechanism. The pre-transformed material dispenser may hold at least an amount of powder material sufficient for dispensing at least about one, two, three, four or five layers. The material sufficient to dispense about a layer may be more than the material dispensed for the formation of the layer. For example, the material may be sufficient to dispense the layer and retain an angle of repose to control dispersion of a requested amount of material. The pre-transformed material dispenser (e.g., an internal reservoir) may hold at least an amount of powder material sufficient for at most one, two, three, four or five layers. The pre-transformed material dispenser reservoir may hold an amount of material between any of the aforementioned amounts of material (e.g., sufficient to a number of layers from about one layer to about five layers). The pre-transformed material dispenser reservoir may hold at least about 20 grams (gr), 40gr, 50gr, 60gr, 80gr, 100gr, 200gr, 400gr, 500gr, or 600gr of pre-transformed material. The pre-transformed material reservoir may hold at most about 20gr, 40gr, 50gr, 60gr, 80gr, 100gr, 200gr, 400gr, 500gr, or 600gr of pre-transformed material. The pre-transformed material dispenser reservoir may hold an amount of material between any of the aforementioned amounts of pre-transformed material dispenser reservoir material (e.g., from about 20 gr to about 600 gr, from about 20gr to about 300 gr, or from about 200 grto about 600 gr.). Pre-transformed material may be transferred from the bulk reservoir to the material dispenser by any analogous method described herein for exiting of pre-transformed material from the material dispenser. Transfer of the starting material from the bulk reservoir to the material dispenser may take place in the ancillary chamber, e.g., in the garage.

[0218] At times, the pre-transformed material in the bulk reservoir and/or in the material dispensing mechanism is temperature adjusted, e.g., is preheated, cooled, is at an ambient temperature or maintained at a predetermined temperature.

[0219] In some embodiments, the layer dispensing mechanism includes components comprising a material dispensing mechanism, material leveling mechanism, material removal mechanism, or any combination or permutation thereof. In some configurations, the material dispensing mechanism comprises a material dispenser and a material remover. The material dispenser may be operatively coupled to an agitator that causes at least a portion of the pretransformed material within the material dispenser to vibrate. Vibrate may comprise pulsate, throb, resonate, shiver, tremble, flutter or shake. For example, the agitator may cause one or more portions of the material dispenser body to vibrate. The one or more portions of the material dispenser may comprise a side, or a panel (e.g., a gate), of the internal reservoir of the material dispenser. For example, the agitator (e.g., vibration mechanism) may cause at least a portion of the exit port of the material dispenser to vibrate. For example, the agitator may cause one or more components of the material dispenser to vibrate. For example, the agitator may cause the material dispenser to vibrate. The agitator may cause the starting material disposed in the material dispenser to vibrate, e.g., without (e.g. substantially) vibrating the body of the material dispenser. The agitator may be any agitator described herein. The material dispenser may comprise a container (e.g., an internal reservoir of pre-transformed material). [0220] At times, the material dispenser comprises an agitation component. The agitation component (e.g., vibrator, actuator, or the like) can be located adjacent to and/or in contact with one or more surfaces of the material dispenser. For example, the agitation component may be in contact with an inner surface of a body of the material dispenser. For example, the agitation component may be in contact with an outer surface of a body of the material dispenser. For example, the agitation component may separate (e.g., isolated) from the surfaces of a body of the dispenser and disposed in the dispenser. For example, the agitator may comprise a wave guide that is inserted into an internal reservoir of the material dispenser, e.g., into the container of the material dispenser.

[0221] At times, the agitator is controlled, e.g., automatically by at least one controller such as the one disclosed herein. The vibratory motion may be performed continuously or intermittently. The vibrations may be homogenous during a deposition cycle. The vibrations may vary during a deposition cycle. The vibratory motion may be performed during the deposition of a planar layer of pre-transformed material, or a portion thereof. The vibratory motion may be performed during (e.g., as part of) a printing cycle of at least one 3D object. The vibratory movement of the material dispenser may be controlled statically. The vibrating movement of the material dispenser may be controlled dynamically (e.g., during deposition of at least a portion of a planar layer of material), e.g., in real time. The vibrating movement of agitation component can be utilized to control fluidization of pre-transformed material disposed in the material dispenser during one or more processes of the 3D printing, e.g., to dispense material onto a target surface to form, or extend, a material bed. For example, vibrating movement of the agitation component can induce a flow of pre-transformed material (e.g., an “ON” state) from a material dispenser of a layer dispensing mechanism, where no vibrating movement of the agitation component can reduce (e.g., stop) a flow of pre-transformed material (e.g., an “OFF” state) from the material dispenser.

[0222] In some embodiments, the actuator is operatively coupled to at least one controller (herein collectively “controller”). The controller may be coupled to at least one sensor (e.g., positional, optical, or weight). The controller may control the starting of an actuator’s operation. The controller may control the stopping of the actuator’s operation. The controller may detect a position of the layer dispensing mechanism. The position may be an absolute position nor a relative position, e.g., relative to the build plate or to the piston. The controller may dynamically (e.g., in real-time during the 3D printing) control the actuator, e.g., to adjust the position of the layer dispensing mechanism. The controller may control the amount of movable distance of the layer dispenser. The controller may detect the need to perform dispensing and/or planarization operation on a target surface. The controller may activate the actuator to move the layer dispensing mechanism to a position adjacent to the platform. The controller may be coupled to an agitator and control operation of the agitator, e.g., to dispense starting material onto a target surface. The controller may detect the completion of dispensing a layer adjacent to the platform (e.g., comprising a base - build plate Fig. 1 , 102 and a substrate - piston Fig. 1 , 109). The controller may activate an actuator to move the shaft to retract the layer dispensing mechanism into the ancillary chamber.

[0223] At times, the actuator is operatively coupled, e.g., mechanically coupled, to a transducer configured to induce vibratory motion in the actuator. The frequency of vibration may be at least about 20 Hertz (Hz), 25 Hz, 30 Hz, 35 Hz, 40 Hz, 45 Hz, 50 Hz, 55 Hz, 60 Hz, 65 Hz, 70 Hz, 75 Hz, 80 Hz, 85 Hz, 90 Hz, 95 Hz, 100 Hz, 105 Hz, 110 Hz, 115 Hz, 120 Hz, 125 Hz, 130 Hz, 135 Hz, 140 Hz, 145 Hz, or 150 Hz. The frequency of vibration may be at most about 25 Hz, 30 Hz, 35 Hz, 40 Hz, 45 Hz, 50 Hz, 55 Hz, 60 Hz, 65 Hz, 70 Hz, 75 Hz, 80 Hz, 85 Hz, 90 Hz, 95 Hz, 100 Hz, 105 Hz, 110 Hz, 115 Hz, 120 Hz, 125 Hz, 130 Hz, 135 Hz, 140 Hz, 145 Hz, or 150 Hz. The frequency of vibration may be a range of frequency between any of the aforementioned frequency values (e.g., from about 20 Hz to about 150 Hz, or from about 20 Hz to about 40 Hz, from about 40 Hz to about 100 Hz, or from about 100 Hz to about 150 Hz). The translation velocity of at least one component of the layer dispensing mechanism, may be at most 10 millimeter/second (mm/sec), 20 mm/sec, 30 mm/sec, 40 mm/sec, 50 mm/sec, 60 mm/sec, 70 mm/sec, 80 mm/sec, 90 mm/sec, 100 mm/sec, 110 mm/sec, 120 mm/sec, 125 mm/sec, 130 mm/sec, 140 mm/sec, 150 mm/sec, 160 mm/sec, 170 mm/sec, 180 mm/sec, 190 mm/sec, 200 mm/sec, 250 mm/sec, 300 mm/sec, 400 mm/sec, or 500 mm/sec. The translation velocity of at least one component of the layer dispensing mechanism may be at least 10 millimeter/second (mm/sec), 20 mm/sec, 30 mm/sec, 40 mm/sec, 50 mm/sec, 60 mm/sec, 70 mm/sec, 80 mm/sec, 90 mm/sec, 100 mm/sec, 110 mm/sec, 120 mm/sec, 130 mm/sec, 140 mm/sec, 150 mm/sec, 160 mm/sec, 170 mm/sec, 180 mm/sec, 190 mm/sec, 200 mm/sec, 250 mm/sec, 300 mm/sec, 400 mm/sec, or 500 mm/sec. The translation velocity of at least one component of the layer dispensing mechanism may be a range of velocity between any of the afore-mentioned velocity values (e.g., from about 10mm/sec to about 500 mm/sec, from about 10 mm/sec to about 125 mm/sec, from about 130 mm/sec to about 300 mm/sec, or, from about 300 mm/sec to about 500 mm/sec). The travel distance of the layer dispensing mechanism within the processing chamber may be at least about 10 millimeter (mm), 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 75 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 340 mm, 360 mm, 380 mm, 400 mm, 420 mm, 440 mm, 460 mm, 480 mm, 500 mm, 520 mm, 540 mm, 560 mm, 575 mm, 580 mm, 590 mm, 600 mm, 620 mm, 650 mm, 670 mm, 690 mm or 700 mm. The travel distance of the layer dispensing mechanism within the processing chamber may be At most about 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 75 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, 220 mm, 240 mm, 260 mm, 280 mm, 300 mm, 320 mm, 340 mm, 360 mm, 380 mm, 400 mm, 420 mm, 440 mm, 460 mm, 480 mm, 500 mm, 520 mm, 540 mm, 560 mm, 575 mm, 580 mm, 590 mm, 600 mm, 620 mm, 650 mm, 670 mm, 690 mm or 700 mm. The travel distance of the layer dispensing mechanism may be a range of distance between any of the afore-mentioned distance values (e.g., from about 10 mm to about 700 mm, from about 10 mm to about 300 mm, from about 10 mm to about 75 mm, from about 75 mm to about 575 mm, from about 100 mm to about 400 mm or from about 400 mm to about 700 mm). [0224] In some embodiments, pre-transformed material may reside within the body of the material dispenser, e.g., with in the container of the material dispenser. The container may have a uniform or a non-uniform shape. The container may comprise at least one portion of a wall that is slanted towards an exit port. The slanted portion may facilitate flow of material through the exit port (e.g., during the dispensing the pre-transformed material). The container may comprise an internal cavity. The internal cavity may facilitate directional flow of the material. The container may comprise an exit port. The exit port may be on a bottom surface, and/or at a wall surface of the container. The exit port may or may not be part of a nozzle. The wall may be a side wall. The exit port may facilitate (e.g., allow) dispensing of pre-transformed material towards the platform and/or gravitational center. At least one wall of the container may be translatable (e.g., adjustable). The at least one wall of the container may be controlled to adjust the exit port of the container (e.g., adjust the gap of the exit port). For example, the lateral distance between a first wall and a second wall opposing the first wall, may be adjusted to facilitate a requested exit port (e.g., narrow, or wide). The lateral distance between the walls of the container that form the exit port may be at most about 0.1 millimeter (mm), 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 15mm, 20mm, 25mm, 30mm, or 50mm. The lateral distance may be a range of distance between any of the afore-mentioned values (e.g., from about 0.1 mm to about 50 mm, from about 0.1 mm to about 1 mm, from about 1 mm to about 4 mm, from about 4 mm to about 10 mm, or from about 7 mm to about 20 mm, or from 5mm to 50mm). The container may be operatively coupled to at least one controller. The at least one controller may facilitate adjustment of the distance between a first wall and a second wall of the container. The adjustment may be done before, after or during at least a portion of the 3D printing (e.g., the entire 3D printing). For example, the adjustment may be before, after, and/or during dispensing a layer of pre-transformed material. The control may be manual and/or automatic (e.g., using a controller). The one or more walls of the container may comprise a smooth internal surface (e.g., that comes into direct contact with at least a portion of the pretransformed material within the material dispenser). Smooth surface may be of an Ra value of at most about 3 m, 4 pm, 5 pm, 6 pm, 7 pm, 8 pm, 9 pm, 10 pm, 30 pm, 40 pm, 50 pm, 75 pm, or 100 pm. Smooth surface may be of an Ra value that is between any of the afore-mentioned values (e.g., from about 3 pm to about 100 pm, from about 3 pm to about 40 pm, or from about 3 pm to about 10 pm). A measure of the average roughness (Ra) is a roughness parameter that measures the deviation of a surface from a mean height. The smooth internal surface may exhibit a small, negligible, and/or insubstantial amount of friction with the pre-transformed material (e.g., relative to the intended purpose of dispensing the pre-transformed material from the exit port of the material dispenser). The small, negligible, and/or insubstantial amount of friction may facilitate (e.g., easy, uninterrupted, and/or continuous) dispensing of the pretransformed material in a requested manner. The one or more smooth walls of the container may be formed by a polishing process (e.g., soda-blasting, vapor polishing, flame polishing, paste polishing, or chemical-mechanical polishing). The one or more smooth walls of the container may be formed by coating a wall with a coating (e.g., a polished material). Examples of polished material include mirror, or polished stainless steel. The coating may alter the surface properties. For example, the coating may alter the adhesion, attraction and/or repulsion of the pre-transformed material to the internal surface. For example, the coating may reduce the adhesion and/or attraction of the pre-transformed material to the internal surface. For example, the coating may cause the pre-transformed material to repel from the internal surface. The surface structure of the internal surface may comprise a low attachment surface (e.g., a Lilly pad, or shark skin type surfaces). The container may comprise an entry opening port. The entry opening may be located on a top surface of the container. Top may be in a direction opposite to the platform and/or gravitational center. The material may reside in the container until the exit port may be opened to allow dispensing of the material. In some embodiments, the entry opening may have an area (e.g., or FLS) that is different than that of the exit port. For example, the entry opening may have a wider opening than the exit port. At times, the entry opening may be of (e.g., substantially) the same area (e.g., or FLS) as the exit port. The exit port may be operatively coupled to an obstruction. Examples of an obstruction includes one or more sectional doors, a sliding door (e.g., Fig. 16, 1670), a folding door, a swing-out (e.g., Fig. 16, 1630) or a roll-up door. The obstruction may be physically and/or operatively coupled at a position adjacent to the exit port. Physically coupled may comprise a hinge and/or a motor. The position adjacent to the exit port may comprise a position at the external surface of the material dispenser. Adjacent may be on a (e.g., external) bottom surface of the container. Adjacent may be below the exit port. The obstruction may be physically and/or operatively coupled via a mechanical connector, a controlled sensor, a magnetic connector, an electro-magnetic connector, or an electrical connector. The obstruction may be operatively coupled to at least one controller. The controller may actuate the exit port to which the obstruction is operatively coupled to e.g., at a requested and/or predetermined time. The controller may receive feedback from at least one sensor. The opening and/or closing of the obstruction may be controlled based at least in part on the feedback from the sensor. For example, a height (e.g., optical) sensor may detect the height of a dispensed layer. The controller may receive a detected height input. The controller may adjust the amount of pre-transformed material to be dispensed based at least in part on the detected height. To adjust the amount of material to be dispensed, the controller may adjust the lateral distance of the exit port and/or the position of the obstruction. The detected height may be at least about 200 microns (pm), 250 pm, 300 pm, 350 pm, 400 pm, 450 pm, 500 pm, 550 pm, 600 pm, 650 pm, 700 pm, 750 pm, 800 pm, 850 pm, 900 pm or 950 pm. The detected height can be between any of the afore-mentioned amounts (e.g., from about 200 m to about 950 pm, from about 200 pm to about 500 pm, from about 500 pm to about 700 pm, or from about 700 pm to about 950 pm). At times, the material within the container may actuate (e.g., push) the obstruction (e.g., to open the exit port and allow pre-transformed material to exit the material dispenser). An actuator may facilitate sliding, swinging-out, or rolling the obstruction to facilitate dispensing of the material from the exit port of the material dispenser. A controller may control the actuator (e.g., in real-time during at least a portion of the 3D printing). The obstruction may at least partially (e.g., fully) open when dispensing the material from the exit port (e.g., before, after, and/or during the 3D printing). The degree to which the obstruction obstructs the exit port may be controlled (e.g., in real time during the dispensing). The degree to which the obstruction obstructs the exit port may regulate (e.g., in real time during the dispensing) the amount of pre-transformed material that exits the material dispenser. The obstruction may be closed once a sufficient amount of pre-transformed material has been dispensed at a position. For example, the obstruction may be closed at times during a portion of a deposition cycle of a pre-transformed material layer. For example, the obstruction may be closed once a layer of material has been dispensed. In some embodiments, the target surface includes a surface at which an energy beam (e.g., laser beam, electron beam, and/or ion beam) is directed. For example, the target surface can correspond to an exposed surface of a material bed used in a selective sintering operation. In some embodiments, the target surface includes surfaces of a pre-transformed material that is not in a material bed. The material dispensing mechanism may not be in contact with the target surface (e.g., exposed surface of a material bed). The target surface can comprise a suitable surface of a material bed used for printing 3D object(s), or a build plate on which such material bed can be deposited. The layer dispensing mechanism (e.g., comprising the material dispensing mechanism) may translate in a parallel manner (e.g., in a direction that is (e.g., substantially) parallel) with respect to the platform (e.g., a surface (e.g., top surface) of the platform (e.g., base)), e.g., as it translates laterally. The layer dispensing mechanism may translate in a manner that deviates from being parallel with respect to the platform. For example, the layer dispensing mechanism may approach the platform, e.g., as it travels laterally. For example, the layer dispensing mechanism may sag towards the platform, e.g., as it translates laterally. The dispensed layer of material may form a material bed above the platform (e.g., base).

[0225] The material dispensing mechanism may comprise a container (e.g., reservoir) configured to contain pre-transformed material within a cavity of the container. The container can be at least a portion of the body of the material dispenser. The material dispensing mechanism may comprise an obstruction which may, in a closed state, obstruct an exit port of the material dispenser through which the pre-transformed (e.g., starting) material exits the material dispenser, e.g., during dispensing operation. The obstruction may be configured to obstruct the exit port of the material dispenser at least partially. The exit port may be referred to herein also as the “exit opening.” The obstruction may open such as swing-out, e.g., to allow the pre-transformed material to exit from the container through the exit port of the material dispenser. The obstruction may close such as swing-in, e.g., to prevent the pre-transformed material from exiting from the container through the exit port of the material dispenser. Opening or closing of the obstruction (e.g., swinging-out) may comprise swinging about a rotational axis (e.g., using a hinge). Opening or closing of the obstruction may comprise sliding along railing. The obstruction may swivel, or slide. The obstruction may be physically coupled to an edge of a wall of the container and the exit port. The obstruction may comprise a panel, e.g., as disclosed herein. In some embodiments, a material dispensing mechanism comprises a plurality of obstructions arranged with respect to a plurality of respective openings in the container. At least one of the plurality of obstructions may open to allow dispensing of pre-transformed material from the exit port. Openings of at least two of the plurality of obstructions may be synchronized. The opening may be reversible, e.g., the obstruction may open and close the exit port of the material dispenser. Movement of at least two of the plurality of obstructions may not be synchronized. Synchronized may be according to the timing and/or magnitude of their respective opening. At least two of the obstructions may be operatively coupled to the same controller. At least two of the obstructions may each be operatively coupled to a controller. Each of the obstructions may be independently controlled. For example, a first opening obstruction may open one exit port to dispense material while the second opening obstruction may close another exit port. At times, a material dispensing mechanism comprises a sliding obstruction. The obstruction may slide in a lateral direction (e.g., along the X-axis). Movement of the obstruction may be controlled. Controlling may include sliding the obstruction at least in part, such that at least a portion of the exit port allows dispensing of the pre-transformed material (e.g., while a portion of the exit port remains closed). The amount of pre-transformed material dispensed may be controlled, e.g., by controlling the degree in which the port is open (e.g., degree of sliding) of the obstruction relative to the exit port. The layer dispensing mechanism may comprise actuator(s) increasing the flowability of the pre-transformed material disposed in the cavity of the material dispenser, to egress through its exit port. Examples of 3D printing systems and their components (e.g., layer dispensing mechanism), 3D printing processes, 3D objects, control systems, and software can be found in International Patent Application Serial Number PCT/US15/36802, and in International patent application serial number PCT/US16/66000, each of which is entirely incorporated herein by references.

[0226] Fig. 16 shows examples of a vertical cross section of material dispensing mechanisms that comprise various obstructions to its exit port. Fig. 16 shows an example of a material dispensing mechanism 1600 that dispenses a material fall 1620 (e.g., pre-transformed material) to form a layer of material 1645 on a platform 1641 . The material dispensing mechanism can translate in lateral directions 1640. The material dispensing mechanism comprises a body including a container 1634 having a side wall 1610. Container 1634 may be configured to retain the pre-transformed material 1639. The material dispensing mechanism comprises an obstruction 1630. As depicted in the example of Fig. 16, obstruction 1630 swings-out in a motion 1625 to allow material dispensing from the container through exit port 1632. The swinging-out motion 1624 is about a rotational axis (e.g., using a hinge). The swinging out motion may be reversible, e.g., swinging out to open and swinging in to close the exit port. The obstruction is physically coupled to an edge of a wall of the container 1634 and the exit port. Fig. 16 shows an example of a material dispensing mechanism 1651 that comprises multiple obstructions 1650 and 1652. The obstructions 1650, 1652 swing outs with a motion 1655 to allow dispensing of material from the exit port. The motions 1655 of opening obstructions 1650, and 1652 may be synchronized or not be synchronized. The obstructions 1650, 1652 may be operatively coupled to the same controller or may be operatively coupled to different controllers. The obstructions 1650, 1652 may be independently controlled. For example, a first opening obstruction 1650 may swing out to dispense material while the second opening obstruction 1652 may be closed. The swinging motion of the of these obstructions may be reversible, e.g., open an close, and close and open. Fig. 16 shows an example of a material dispensing mechanism 1660 that comprises a sliding opening obstruction 1670 that can slide from side to side according to arrow 1672. The obstruction may slide in a lateral direction (e.g., along the X-axis 1672). The material dispensers in examples 1600, 1651 , and 1660 are depicted in relation to gravitational vector 1699 directed towards gravitational center G.

[0227] In some embodiments, the material dispenser comprises at least one agitator. In some embodiments, an agitator facilitates a vibrating motion of a portion of the layer dispensing mechanism. The vibrating motion may include a dithering movement. The dithering movement may have a length of at most about 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.7 mm, 2.8 mm, 3.0 mm, 4.0 mm, 5.0 mm, 6.0 mm, 7.0 mm, 8.0 mm, 9.0 mm, or 9.9 mm. The dithering movement may have a length that may be a range between any of the afore-mentioned values (e.g., from about 0.1 mm to about 9.9 mm, from about 0.1 mm to about 1 .0 mm, from about 1.0 mm to about 5.0 mm, or from about 5.0 mm to about 9.9 mm).

[0228] In some embodiments, the vibrations of the pre-transformed material disposed in the material dispenser may be directional. For example, the directional vibrations may coincide with the direction of movement of the material dispenser along a path, oppose that direction. In some embodiments, the vibrations of the pre-transformed material disposed in the material dispenser may be non-directional, e.g., in a random direction. Fig. 17 shows examples of a (e.g., successive steps in a) vibrating motion of a component of the layer dispensing mechanism (e.g., material dispensing mechanism) that traverses in the direction 1740. Fig.17 illustrates an example 1700 of moving a component of the layer dispensing mechanism, e.g., material dispensing mechanism 1738 vibrating directionally in a forward direction 1717 relative to a target surface, e.g., platform 1730 and/or relative to the exposed surface 1731 of the material bed. In the example shown in 1700, the directional vibration in the direction 1717 coincides with the direction at which the material dispenser 1738 is traveling, which is 1740. Fig.17 illustrates an example 1741 of moving the material dispenser 1744 in a forward direction 1748 while directionally vibrating it in a backward direction 1746 relative to the platform 1750, relative to its previous position 1745, and/or relative to the target surface. In the example shown in 1741 , the directional vibration in the direction 1746 opposes the direction at which the material dispenser 1744 is traveling, which is 1748. Fig.17 illustrates an example 1761 of moving the material dispenser 1764 in a forward direction 1768 that coincides with a directional vibration in the direction 1766, relative to a previous position 1765 of material dispenser 1764. The material dispensing mechanisms in examples 1700, 1761 , and 1741 are depicted in relation to gravitational vector 1799 directed towards gravitational center G.

[0229] At times, at least one component of the layer dispenser (e.g., the material dispenser) comprises features that allow for the dispensing of pre-transformed material without the use of an obstruction. The obstruction may constitute a moving mechanism (e.g., hinge leaf, flap, gate, lid, shutter, or joint). The obstruction may comprise the panel. In some embodiments, the obstruction may not be moveable. The obstruction may be an integral part of the material dispenser or may be operatively coupled to the material dispenser. For example, a particulate material (e.g, particles of a powdered material) may become lodged in the obstruction (e.g., in the moving mechanism) such that the dispensing mechanism (or portions thereof) may require replacement and/or maintenance (e.g, cleaning). For example, a particulate material (e.g., particles of a powdered material) may become lodged in the obstruction such that the 3D printing cycle must be stopped. For example, the obstruction may couple to a body of the material dispenser by a fastener, by a railing. The fastener may comprise a hinge. In some embodiments, the at least one component of the layer dispenser (e.g., the material dispenser) does not include (e.g., is devoid of) the moving mechanism. Absence of the moving mechanism may improve a functional reliability of the component and/or reduce the amount of maintenance and/or replacement of the component. Fig. 18 illustrates a vertical cross-sectional example of a material dispenser 1802 in accordance with some embodiments. Fig. 18 illustrates the example material dispenser 1802 and Fig. 18 illustrates an example 1840 of an inset view 1801 showing a close-up of a portion of the material dispensers 1802, and 1822. The material dispenser mechanism 1802 and insert view 1840 are depicted in relation to gravitational vector 1899 directed towards gravitational center G. Material dispenser 1802 includes a waveguide 1820 disposed in the material reservoir cavity that includes the particulate material 1803. Waveguide 1820 is coupled to transducer (e.g., wave guide generator) 1821. Material dispenser 1802 includes slanted walls 1805 and 1808 and a bottom portion including a retaining member 1819 connected to panel 1806 that is the bottom of the material dispenser 1802. Material dispenser 1802 has an exit port 1807 through which material exits according to angle of repose 1814 (a_r) in material fall 1810 to form a material bed disposed on a platform or base 1811. Material dispenser 1802 has a back edge. Exit opening 1807 is disposed between the panel 1806 and an upper edge 1817 of the exit opening, with respect to gravitational vector 1899. The material dispenser can include a bottom portion (e.g., 1806) that can (e.g., temporarily) retain at least a portion of the pre-transformed material within the material dispenser. The pre-transformed material can (e.g., temporarily) accumulate at the bottom portion, supported by the walls of the bottom portion and the force of gravity. The material dispenser may have at least one slanted (e.g., side) wall, e.g., that tapers towards the bottom portion, thus forming a tapered reservoir for the starting material to be dispensed (e.g., the pre-transformed material). In some cases, the material dispenser has a funnel shape that converges at the bottom portion. The bottom portion can include a lip (also referred to as a ledge) that extends from the bottom portion. The lip can correspond to a projecting edge that ends at an exit port where the material can exit the material dispenser. The lip may extend beyond a horizontal cross section of the converging reservoir bottom. The extend of extension may consider (e.g., correlate to) an angle of repose of the material to be dispensed. The exit port can be at least partially defined by the bottom panel (e.g., lip) and an upper edge of the exit port. The exit port can be positioned in a back portion of the material dispenser. The lip and back edge can facilitate temporary retention of the material within the bottom portion, e.g., in accordance with an angle of repose (e.g., a_r) of the material. Without wishing to be bound to theory, the material can be retained within the bottom portion when the material dispenser (e.g., in a stationary state, a temporary stationary state, or a moving state) when conditions of the following equation 1 are met: tan a_r r = — Ll

where Li is a lateral (e.g., horizontal) length from the back edge to the end of the lip; L₂ is a height (e.g., longitudinal length) of the lip as measured from the back edge; and a_r is the angle of repose of the material. The angle of repose a_r can vary depending on factors such as the type of material (e.g., composition of the material) and the particles size of the material. In some embodiments, ranges from about 0.2 and about 1 , from about 0.2 to about 0.5, from about 0.5 to about 1 , from about 0.5 to about 0.8, from about 0.3 to about 0.6, or from about 0.8 to about 1.

[0230] In some embodiments, the layer dispenser comprises a material dispenser. The material flowing out of the material dispenser can be agitated, e.g., to facilitate its flow. The agitative motion (e.g., vibratory motion) may comprise an agitator or motion of the material dispenser (e.g., agitation by an actuator of the layer dispenser). In some embodiments, the agitative motion is devoid of a back and forth (e.g., stuttering) motion of the material dispenser, e g., and relies on the motion of another agitator such as a waveguide. The material dispenser may comprise a lip adjacent to its exit port. The lip can include a retaining member. The retaining member may be an impediment to the material fall. In some embodiments, the retaining member extends (e.g., upward) from an end of the lip at angle. The retaining member can facilitate retention of the material within the bottom portion. In some instances, the material dispenser is operationally coupled with one or more actuators (e.g., that is/are operationally coupled with one or more controllers) that provides the (e.g., forward and/or backward) agitative motion. The motion may be a linear motion. The motion may be in at least two dimensions, e.g., in three dimensions. In some cases, the stuttering motion includes a vibrating motion. In some instances, the material dispenser is operationally coupled with a plurality of actuators (e.g., that are operationally coupled with one or more controllers) that provide (A) a stuttering motion (e.g., forward and/or backward agitative motion) and (B) a vibratory motion. In some cases, the (A) stuttering motion is separate from (B) the vibratory motion. The stuttering and/or vibratory motion may be of the material dispenser and/or of at least a portion of the pre-transformed material disposed in a cavity of the material dispenser, e.g., in a reservoir of the material dispenser. In some embodiments, the vibrating motion includes vibrations at a frequency, e.g., an ultrasonic frequency. The frequency may facilitate a fallout of the material from the material dispenser at a rate. The rate may facilitate a (e.g., substantially) planar deposition of the material. The rate may facilitate a (e.g., substantially) homogenous deposition of the material, e.g, across the deposition area. The deposition area may be at least a portion of a platform or an exposed surface of a material bed. In some cases, the repetitive (e.g, stuttering) motion is accomplished by one or more actuators other than those used to move the material dispenser, e.g., one or more agitators such as the ones disclosed herein.

[0231] At times, the material dispensing mechanism can be a sonic (e.g., ultrasonic) dispensing mechanism, e.g., comprising sonically induced agitation. The mechanism that is configured to deliver the pre-transformed material to the material bed can be an agitating material dispensing mechanism. The material dispensing mechanism may comprise an agitator such as a shaker. The agitator (e.g., transducer thereof) can be, for example, a piezo-electric device, sonic (e.g., ultrasonic) device, powder hopper, wheel, or the like. The agitator may be coupled to the material dispensing mechanism and configured to fluidize at least a portion of the pre-transformed material retained by the material dispensing mechanism, for example (I) retained within the material dispensing mechanism, (II) retained by a panel (e.g., a gate) of the material dispensing mechanism, (III) retained by a reservoir of the material dispensing mechanism, or (IV) any combination thereof. At times, a material dispensing mechanism may include two or more agitators. At least two of the agitators may be coupled to a same component of the material dispensing mechanism. At least two of the agitators may be each coupled to a different components of the material dispensing mechanism. For example, a first agitator may be coupled to a panel of the material dispensing mechanism and a second agitator may be coupled to a body of the material dispensing mechanism. The agitator may be operatively coupled to an agitation transducer, wired and/or wirelessly. The transducer may be located in various locations relative to the enclosure (e.g., relative to the processing chamber). For example, the transducer may be located outside the processing chamber, e.g., external to an atmosphere of the processing chamber. The agitator may be operatively coupled to the material dispensing mechanism via (I) flexible coupling/cabling, (II) a wired communication channel, (III) a wireless communication channel, or (IV) any combination thereof. For example, the transducer may be located inside the enclosure (e.g., inside the processing chamber). The transducer located in the enclosure may be isolated from an interior atmosphere of the enclosure, e.g., hermetically sealed from the atmosphere of the processing chamber. Isolation from the interior atmosphere may be such that the gas borne particulate matter will not contaminate the transducer. Isolation from the interior atmosphere may or may not be gas tight. [0232] In some embodiments, a layer dispensing mechanism comprises a dispenser configured to retain pre-transformed material, e.g., a starting material for the 3D printing process. The dispenser may comprise a component that is agitated (e.g., mechanically or sonically agitated) to couple vibratory motion to the panel such as to the gate. For example, the dispenser may comprise a transducer to couple ultrasonic energy to the panel.

[0233] In some embodiments, a layer dispensing mechanism comprises, or is operatively coupled to, a panel. The panel may comprise a gate. A transducer may be coupled to the panel and be configured to induce a vibratory motion (e.g., ultrasonic vibrations) in the panel. The vibratory motions of the panel can be sufficient to fluidize the pre-transformed material disposed in the layer dispensing mechanism, e.g., disposed in a reservoir of the material dispenser such as in a cavity of the body of the material dispenser. The vibratory motion can be micrometer scale motion. The vibratory motion can be at any frequency or frequency range disclosed herein. The vibratory motion of the panel may depend at least in part on the fluidization of the starting material to be deposited by the material dispenser. The fluidization of the starting material may depend at least in part on (A) a starting material type, (B) atmospheric conditions in a dispenser environment, (C) mechanical configuration of the dispenser, (D) a manner of the dispenser translation (e.g., speed and/or acceleration), or (E) any combination thereof. The panel may be a waveguide, where a transducer is coupled to the panel and configured to induce sonic vibration (e.g., ultrasonic vibration) in the waveguide. The panel may comprise a shutter, flap, or sliding mechanism, which is coupled to the material dispenser of the layer dispensing mechanism. The starting material may comprise particulate matter, e.g., powder. The particulate matter may be solid or semi-solid (e.g., gel).

[0234] At times, the material dispensing mechanism is configured to deliver the pretransformed material to the target surface can comprise an agitator comprising a vibrating mesh. The vibration may be formed by an ultrasonic transducer, a piezo-electric device, a rotating motor (e.g., having an eccentric cam), or any combination thereof. The ultrasonic and/or agitating material dispensing mechanism can vibrate the pre-transformed material in one, two, or three dimensions. The frequency of an ultrasonic and/or agitating disturbance of the material dispenser can be chosen such that pre-transformed material is delivered to the target surface at a predetermined rate. The ultrasonic and/or agitating dispenser can dispense pre-transformed material onto the target surface from a location above the target surface, relative to a gravitational center. The pre-transformed material may be dispensed using at least in part a gravitational force. The ultrasonic and/or otherwise agitating dispenser can be a top-dispenser that dispenses the pre-transformed material from a position above the target surface, relative to a gravitational center. The agitator may comprise a spring. The agitator may be an electric or hydraulic agitator. The material dispensing mechanism can comprise two or more agitators (e.g., an array of agitators). The array of agitators can be arranged linearly, non-linearly, or at random. The array of agitators can be arranged along the exit port of the material dispenser, or in proximity thereto. The material dispenser can comprise multiple opening ports. The array of agitators can be disposed along the array of opening ports (e.g., the multiple openings). The agitators can be arranged along a line, e.g., in a single file. The agitators can be arranged along a linear pattern. The agitators can be arranged along a non-linear pattern. The arrangement of the agitators can determine the rate at which the powder exits the material dispenser. The agitator(s) may reside on a face of the material dispenser.

[0235] At times, the material dispenser may comprise, or be operatively coupled to, an obstruction that comprises a panel. The panel may be a slanted panel. The panel may have a planar surface. An edge of the panel may be oriented parallel to an exposed surface of the material bed. An edge of the panel may be oriented perpendicular to a gravitational axis of the 3D printing system. The panel may be a slab, board, beam, plank, or leaf. The panel may comprise a lip or edge component along a length of the panel to encourage a flow of powder (e.g., a material fall) in a limited direction, e.g., over one edge of the panel. The panel may comprise a waveguide. The panel may be oriented with respect to an exit port of the dispenser such that a surface of the panel is adjacent to and disposed facing towards the exit port of the material dispenser. The panel may be oriented with respect to an exit port of the material dispenser (e.g., a port) at an offset. The panel may be oriented with respect to an exit port of the material dispenser such that there is a minimal (e.g., zero or substantially zero) gap between a surface of the panel and the exit port of the material dispenser. The panel may be oriented with respect to an exit port of the material dispenser such that there is a gap between a surface of the panel disposed facing towards the exit port and the exit port of the material dispenser. The panel may be oriented with respect to an exit port of the material dispenser such that there is an adjustable gap between a surface of the panel disposed facing towards the exit port and the exit port of the dispenser. The adjustable gap may be configured to adapt for powder flowability and/or operation parameters. The panel may be oriented with respect to an exit port of the material dispenser such that there is a gap between a surface of the panel disposed facing towards the exit port and the exit port of the material dispenser, where the size (e.g., a height) of the gap is such that an angle of repose of powder material from the material dispenser through the exit port and onto the panel reduces (e.g., prevents, significantly reduces) a material fall off of an edge of the panel. The panel may be a shutter, flap, sliding mechanism, or another mechanical gate configured to retard or impede a flow of material from the exit port of the material dispenser, e.g., as disclosed herein. The panel can comprise one or more perforations, e.g., holes, slits, mesh or a sieve. The panel may comprise a flexible or a rigid material. The panel may be affixed to the layer dispensing mechanism, e.g., affixed to the material dispenser. The panel may be affixed to a rigid support with respect to an exit port of the material dispenser, e.g., at a fixed offset via a material having an impedance mismatch to a material of the panel and/or a material that is absorptive of ultrasonic vibrations. For example, a material of the absorptive material may have an acoustic impedance of at least about an order of magnitude smaller than an acoustic impedance of a material of the panel. For example, panel may be affixed to a rigid support with respect to an exit port of the material dispenser while substantially free-floated ultrasonically. For example, the panel may be affixed to a rigid support with respect to the exit port by an affixing material comprising a polymer, a resin, an adhesive, or a rubber. The affixing material may comprise an elastomer.

[0236] In some instances, one edge (side) of the panel at the bottom of the material dispenser lies vertically above another edge of that panel with respect to a gravitational center. The panel may comprise a convex or concave portion, e.g., relative to a target surface towards which the material is dispensed by the material dispenser. The angle of the first slanted bottom panel may be adjustable or non-adjustable. The first slanted bottom panel may face the bottom of the target surface. The bottom of the material dispenser may be a slanted panel. The material dispenser may comprise an exit port (e.g., exit opening) that resides within a face of the material dispenser. The face may be the bottom of the material dispenser, which faces the target surface. The face in which the exit port resides may be different than the bottom face of the material dispenser. For example, the face may be a side of the material dispenser. The face may be a face that is not parallel to the target surface. The face may be (e.g., substantially) perpendicular to the average plane formed by the exposed surface of the material bed. The face may be (e.g., substantially) perpendicular to the average plane of the substrate or of the base. A panel in the face (e.g., the entire face) may lean towards the target surface. Leaning may comprise a panel that is curved towards the target surface. The curved panel may have a radius of curvature centering at a point below the bottom of the material dispenser. The curved panel may have a radius of curvature centering at a point above the bottom of the material dispenser. Leaning may comprise a panel forming an acute angle with an average surface of the target surface, or with a plane parallel thereto. For example, a panel at the bottom face of the material dispenser may from an acute or an obtuse angle with the average panel formed by the exposed surface of the deposited layer. The one or more additional panels may comprise a panel that is vertically separated from the exit opening (e.g., port) of the material dispenser by a gap. The gap may be adjustable. The angle of the slanted panel may be adjustable. Additional configurations of material dispensers, layer dispensing mechanism(s), 3D printing systems, processes, and control can be found in International Patent Application serial number PCT/US15/36802, which is incorporated by reference here in its entirety.

[0237] At times, the dispenser comprises a bottom having a first slanted bottom panel. In some instances, one edge (side) of the panel at the bottom of the material dispenser lies vertically above another edge of that panel. The panel may be convex or concave, e.g., relative to the target surface. The angle of the first slanted bottom panel may be adjustable or non- adjustable. The first slanted bottom panel may face the bottom of the enclosure, the substrate or the base. The bottom of the powder dispenser may be a slanted panel. The dispenser may comprise a second panel oriented with respect to the first slanted panel to planarize (e.g., substantially planarize) a flow of material from the exit port of the material dispenser. An angle of orientation of the second panel with respect to the first slanted panel may be adjustable. For example, a surface of the second panel may be oriented parallel to a surface of the first slanted panel. For example, a surface of the second panel may be oriented with respect to a surface of the first slanted panel to form an angle of about 5 degrees (°), 10 °, 25 °, 45 °, 60 °, 75 °, or more. The second panel may be oriented with respect to the first slanted panel to form (e.g., adjust) a dimension of the flow of material from the exit port of the dispenser, for example, reduce a thickness of the flow, increase a planarity of the flow, or the like. The second panel may adjust a path of the flow, for example, direct the material fall to a particular edge of the first panel.

[0238] At times an exit port of the material dispenser comprises a slanted panel. FIG. 19 shows vertical cross sectional examples of material dispensers comprising a panel and an agitator. An example 1900 of a material dispenser 1914 comprises obstruction 1917 that is a panel, and agitator 1912. FIG. 19 shows an example of a material dispenser 1914 having an exit port comprising panel 1917 (e.g., a “doctor’s blade”). The material dispenser 1914 may retain pre-transformed material (e.g., powder 1913). The exit port may comprise a panel or a mesh (or a panel with holes). The exit port may comprise a panel and a mesh (or a panel with holes). The mesh (or panel with holes) may be closer to the exit port than the panel. The panel may be closer to the exit port than the mesh (or panel with holes). The exit port can comprise several meshes and panels. The exit port can comprise a first panel followed by a mesh that is followed by a second panel closest to the surface of the exit port. The exit port can comprise a first mesh followed by a panel, which is followed by a second mesh closest to the surface of the exit port. The first and second panels may be identical or different. The first and second meshes may be identical or different. The material dispenser may comprise a spring at the exit port. Fig. 19 shows various examples of material dispensers. Material dispenser 1914 is configured to translate in any of directions 1916 to deposit by a material fall 1918 material such as powder 1913 from its reservoir onto an exposed surface 1911 of a material bed disposed on platform 1910. Material dispenser 1934 is configured to translate along any of directions 1936 to deposit a material fall 1938 of powder 1939 onto an exposed surface 1931 of a material bed disposed above platform 1930. Material dispenser 1976 is configured to translate along any of directions 1982 to deposit a material fall 1979 of powder 1978 onto an exposed surface 1971 of a material bed disposed above platform 1980. Fig. 19 illustrates an example 1900 of a material dispenser 1914 in accordance with some embodiments. The agitator may reside next to the exit opening (e.g., port). For example, agitator 1912 resides externally on a panel 1920 (e.g., slanted panel) of dispenser 1914. For example, the agitator 1904 resides on a panel 1940 of dispenser 1934, as depicted in example 1950. For example, the agitator 1974 resides internally on a panel (e.g., an obstruction in the exit port), which agitator 1974 is disposed within the material dispenser 1976 and can reside such that the agitator 1974 is at least partially covered by pre-transformed material 1978, as depicted in example 1970. In another example (not shown in Fig. 19), the agitator can reside within the material dispenser such that the agitator is disposed above the pre-transformed material retained within a cavity of the material dispenser. The material dispensing mechanisms in examples 1900, 1950, and 1970 in the example shown in Fig. 19, are depicted in relation to gravitational vector 1999 directed towards gravitational center G. For example, the agitator can reside within the material dispenser without contacting an inner wall of the dispenser and be at least partially disposed within the pre-transformed material retained within the material dispenser cavity. The material dispenser can comprise a mesh that may or may not be connected to an agitator. The material dispenser may comprise a gate that is configured to vibrate. The agitator(s) can vibrate at least part of the pre-transformed material within the material dispenser (e.g., FIG. 19, 1913). For example, the pre-transformed material disposed adjacent to the exit port of the material dispenser. The agitators(s) can vibrate at least a part of the material dispenser body. The body of the material dispenser (e.g., its reservoir body) may comprise a light material such as a light elemental metal or metal alloy (e.g., aluminum). The agitator(s) can be controlled manually and/or automatically (e.g., by a controller). The agitator frequency may be any of the values mentioned herein.

[0239] At times, the exit port of the material dispenser can comprise a mesh or a plane with holes (collectively referred to herein as “mesh”). The mesh comprises a hole (or an array of holes). The hole (or holes) can allow the pre-transformed material, such as the powder material, to exit the material dispenser, e.g., upon agitation of the pre-transformed material.

[0240] In some embodiments, the material dispenser comprises meshes. Movement of the meshes may cause the pre-transformed material in the material dispenser to become flowable, e.g., by being vibrated. At times, at least one of the two or more meshes may be movable, e.g., Fig. 20, 2000. The movement of the two or more meshes may be controlled manually and/or automatically (e.g., by a controller). The relative position of the two or more meshes with respect to each other may determine the rate at which the pre-transformed material passes through the hole (or holes) of the mesh. The FLS of the holes may be electrically, thermally, and/or magnetically controlled. For example, the mesh may be heated or cooled. The temperature of the mesh may be controlled manually or by a controller. The holes of the mesh can shrink or expand as a function of the temperature or electrical charge of the mesh. The mesh can be conductive. The two meshes may have at least one position where no pre-transformed material can pass through the exit port. The two meshes may have a least one position where a maximum amount of pre-transformed material can pass through the exit port. The two meshes can be identical or different. The size of the holes in the two meshes can be identical or different. The shape of the holes in the two meshes can be identical or different. The shape of the holes can be any hole shape as described herein. FIG. 20 shows an example of a material dispenser 2000 having an exit port 2027 having two meshes or two planes with holes. FIG. 20 shows an example 2000 where the extensions of two meshes 2022 and 2026 can be translated vertically. Optionally, material dispensers 2000, 2050 may comprise one or more agitators. The agitator(s) may be located with respect to the material dispenser in any form described herein, e.g., adjacent or and/or in contact with a surface of the material dispenser. Material dispenser 2000 may be configured to translate along any of directions 2029 to deposit a material fall 2028 of pre-transformed material (e.g., powder) 2023 onto an exposed surface 2021 of a material bed disposed above platform 2020. Material dispensers 2000 and 2050 are depicted in relation to gravitational vector 2099 directed towards gravitational center G.

[0241] At times, the material dispenser comprises one or more additional panels. The one or more additional panels may comprise a conveyor. The conveyor can move in the direction of movement of the material dispenser, or in a direction opposite to the direction of movement of the material dispenser. Fig. 20 shows an example of a material dispenser 2050 having a slanted bottom panel 2039, and an additional panel 2036 that constitutes an obstruction. The material dispenser comprises a conveyor 2040. The material dispenser can move in any of directions 2038. The direction of movement of the conveyor can be the same, or opposing, the direction of movement of the material dispenser. In the example shown in Fig. 20, material dispenser 2050 retains pre-transformed material 2033, and deposits it via material fall 2037 onto an exposed surface 2031 of a material bed disposed above platform 2030.

[0242] In some embodiments, the material dispenser may comprise at least one agitator, e.g., as disclosed herein. For example, any of the material dispensers depicted in the examples in figures 16-24, and 26-27 may comprise any of the agitators disclosed herein, e.g., although the agitators may not be shown in the figures. For example, any of the material dispensers depicted in the examples in figures 16-24, and 26-27 that depict agitators, may comprise additionally any of the agitators disclosed herein, e.g., although the additional agitators may not be shown in the figures.

[0243] At times, the material dispenser comprises an obstruction such as a panel (e.g., a gate) operatively coupled to a transducer. The panel may be a waveguide (e.g., an ultrasonic waveguide) operatively coupled to a transducer. In some embodiments, the waveguide may be oriented with respect to an exit port of the material dispenser such that a gap is formed between a surface of the waveguide and the exit port of the material dispenser. The gap between a surface of the waveguide and the exit port of the material dispenser can be about 1 .5 millimeters (mm), 1 mm, 0.75 mm, 0.5 mm, 0.3 mm, 0.1 mm, 0.05 mm, 0.025 mm, or less. For example, the gap can be about 0.5 mm, 0.75, 1 mm, or greater. For example, the gap can be substantially (e.g., nearly) zero millimeters. For example, the gap can be from about 0.5 mm to about 0.1 mm, from about 0.6 mm to about 0.4 mm, or from about 0.6 mm to about 0.05 mm. Pre-transformed material (e.g., powder material) retained within the dispenser may be held by tension (e.g., compression tension) within the gap between the exit port of the material dispenser and the surface of the waveguide (i) while the waveguide is stationary or (i) while a vibratory motion of the waveguide is below a threshold of fluidization of the pre-transformed material, e.g., particulate material such as powder. The vibratory motion of the waveguide can be configured to (i) let pre-transformed material flow out of the dispenser and (ii) dispense a layer of material.

The layer of material can be dispensed Onto a target surface such as an exposed surface of the material bed or a build plate. The layer of material dispensed may have a high level of planarity, e.g., a low level of roughness, relative to a distance between the layer dispensing mechanism and the exposed surface of the material bed. For example, any of the gap and planarity (e.g., roughness) values disclosed herein. Vibratory motion can be induced in the waveguide, e.g., along various axes of the waveguide such as along an axis on an X-Y panel, along a Z-axis, or the like. The pre-transformed material may pour from the exit port of the material dispenser towards the panel. A FLS of the panel may be (i) larger than the FLS of the exit port, and (ii) sufficiently large to retain an angle of repose of the pre-transformed material that is a particulate material. In such instance, the particulate material retained on the panel may shut the exit port of the material dispenser by it forming the heap of particulate material having the angle of repose. Such material may flow when it will be energized, e.g., when it will be vibrated. The vibrations may be formed by an agitator. The agitator may comprise a waveguide. The agitator may be the panel. The waveguide may be the panel. The panel may have a sufficiently large FLS such that minimal (e.g., no) particulate material will flow off of the panel without energizing the particulate material, e.g., without vibrating the particulate material. For example, particulate pre-transformed material (e.g., powder material) located between the exit port of the dispenser and a surface of the panel disposed beneath it separated by the gap can form an angle of repose such that minimal (e.g., zero) powder flows off an edge of the panel that is disposed parallel to the target surface and/or the build plate. Vibratory motion induced in the panel (e.g., that is a waveguide) can reduce the angle of repose of the particulate matter or otherwise fluidize the powder sufficiently to cause it to flow off an edge of the panel. The agitator may have two operative states. For example, in a first operating state, the agitator may induce a fluidization of (i) the pretransformed material retained between the exit port of the dispenser and the surface of the panel, (ii) the pre-transformed material retained within the dispenser, or (iii) a combination thereof. For example, in a second operating state, the agitator may reduce an induced fluidization of (i) the pre-transformed material retained between the exit port of the material dispenser and the surface of the waveguide, (ii) the pre-transformed material retained within the dispenser, or (iii) a combination thereof, by reducing (e.g., stopping) a vibratory motion coupled into the panel. For example, in a second operating state, the dispenser retains below a threshold (e.g., zero or nearly zero) of pre-transformed material such that substantially zero (e.g., zero) material flow occurs from the dispenser, e.g., from the panel thereof. At times, a distance from a central point of an exit port of the material dispenser and an edge of the panel can be selected based in part on (I) a size of the gap between the exit port of the dispenser and a surface of the panel facing the exit port, (II) an angle of repose of the particulate material, (III) environmental temperature during operation, (IV) operating pressure in the environment, (V) level of humidity in the environment during operation, or (V) any combination thereof. At times, a FLS of the panel can be selected based in part on (I) a size of the gap between the exit port of the dispenser and a surface of the panel facing the exit port, (II) an angle of repose of the particulate material, (III) environmental temperature during operation, (IV) operating pressure in the environment, (V) level of humidity in the environment during operation, or (VI) any combination thereof.

[0244] Fig. 21 depicts examples of a material dispensing mechanism comprising a slanted panel. Material dispenser 2100 includes reservoir 2102 configured to retain pre-transformed material 2104 (e.g., a particulate material). Material dispenser 2100 includes a slanted panel 2106 oriented with respect to exit port 2108 of material dispenser 2100, e.g., configured to allow a flow of material to exit from the exit port. The pre-transformed material may flow over an edge of the slanted panel 2106 to form a material fall 2110 that deposits the pre-transformed material onto target surface 2130 to form a deposited layer 2112.

[0245] In some embodiments, a material dispensing mechanism comprises two or more panels. Fig. 21 shows an example of material dispenser 2150 that includes a volume in reservoir 2152 that retains pre-transformed material 2154 (e.g., powder material). Material dispenser 2150 includes a first panel that is a slanted panel 2156 oriented with respect to exit port 2158 of material dispenser 2150 to allow a flow of the pre-transformed material. In the example shown in Fig. 21 , the pre-transformed material flows over an edge of the slanted panel 2156 to form a material fall 2160 which forms a deposited layer 2162 on target surface 2170. A second panel that constitutes an obstruction 2164 is oriented with respect to the slanted panel 2156 and exit port 2158, e.g., to modify the flow of pre-transformed material to form the material fall 2160. For example, the obstruction 2164 can be oriented at an angular offset with respect to an axis 2166 along a surface of the slanted panel 2156, e.g., at about 5 degrees (°), 10 °, 20 °, 50 °, 75 ° or more. The obstruction 2164 can modify a characteristic of the flow of powder forming the material fall 2160, e.g., substantially planarize the material fall 2160. The material dispenser mechanisms 2100 and 2150 are depicted in relation to gravitational vector 2199 directed towards gravitational center G. [0246] At times, a material dispenser comprises an exit port and a panel. The exit port of the material dispenser may comprise a FLS that is sufficiently large to prevent bridging of particulate material at the exit port of the material dispenser, e.g., immediately adjacent to and/or within a region defining the exit port. Bridging may refer to where particulate material interlocks, agglomerates, or bonds together to build an arch such as a bridge above the exit port. The particulate material may comprise powder. For example, an FLS of the exit port may range between about 0.5 millimeters (mm) and about 15 mm. For example, an FLS of the exit port may be about 0.5 mm, 1 mm, 2 mm, 5 mm, 8 mm, 10 mm, 12 mm, or 15 mm. A surface of the panel facing the exit port may be oriented with respect to the exit port and positioned to define a gap between that panel surface and the exit port. For example, a gap defined along a Z-axis oriented with respect to a gravitational center. An FLS of the gap may be sufficiently small such that an angle of repose of the particulate material exiting the exit port and resting on a surface the panel facing the exit port is from about 10 degrees to about 60 degrees. For example, the angle of repose may be at least about 15 degrees, 20 degrees, 35 degrees, 45 degrees, 50 degrees, 55 degrees, or 60 degrees. A lateral dimension of the panel, e.g., a distance from a line extending from a center of an FLS of the exit port intersecting with the surface of the panel facing the exit port to an edge of the panel (e.g., lateral dimension 2218 with respect to axis 2212 in Fig. 22), may be selected to be larger than a lateral spread of the particulate material resting on the panel and may be based at least in part on the angle of repose of the particulate material. The center of the FLS may coincide with a central symmetry feature of the exit port, e.g, when the exit port is symmetric having the central symmetry feature. The symmetry feature can be an axis, a mirror plane, or an inversion point, with the symmetry axis and mirror plane intersecting a plane of the exit port. The lateral dimension of the panel may be related to a gap between the exit port and the surface of the panel facing the exit port by a tangent of the angle of repose of the particulate material. The FLS of the panel may be at least about 3 times (3x), 5x, 10x, 15x, 20x, 25x or more than an FLS of the gap. The FLS the panel can be at least about 0.25 mm, 0.3 mm, 0.4 mm, 0.5 mm, 1 mm, 5 mm, 10 mm, 15 mm, 20 mm, or 25 mm. The FLS the panel can be between any of the aforementioned FLS values, e.g., from about 0.25 millimeters (mm) to about 25 mm. For example, the lateral dimension of the panel may be at least about 3 times (3x), 5x, 10x, 15x, 20x, 25x or more than an FLS of the gap. For example, the lateral dimension of the panel can be from about 0.25 millimeters (mm) to about 25 mm. For example, the lateral dimension of the panel can be at least about 0.25 mm, 0.3 mm, 0.4 mm, 0.5 mm, 1 mm, 5 mm, 10 mm, 15 mm, 20 mm, or 25 mm. The FLS of the panel can be such that in a first operating state the particulate material will accumulate on the surfaced of the panel facing the exit opening, and form an angle of repose distant from the edge(s) of the panel, e.g., such that the particulate material will minimally (e.g., not) flow off the edge(s) of the panel. The FLS of the panel can be such that in a second operating state the particulate material will flow to the surfaced of the panel facing the exit opening, and form an angle of repose on the panel that is extends beyond the edge(s) of the panel, e.g., such that the particulate material flow off the edge(s) of the panel, e.g., to form a material fall such as a particulate material fall. The second operating state may comprise (e.g., kinetically) energizing the particulate material exiting the exit port of the dispenser, e.g., using agitator(s), while the first operating state may exclude such energizing. The first operating state may comprise curbing an angle of repose of the particulate material exiting the exit port of the dispenser to accumulate and (e.g., substantially) remain on the surface of the panel opposing the exit port. The first operating state may exclude (e.g., kinetically) energizing the particulate material such as by use of agitator(s). The second operating state may comprise extending an angle of repose of the particulate material exiting the exit port of the dispenser to flow towards the surface of the panel opposing the exit port and at least in part flow off edge(s) of that surface, e.g., using agitator(s) that (e.g., kinetically) energize the particulate material exiting the exit port. The gap between the exit port and the surface of the pane facing the exit port may be configured such that in a first operating state, the particulate material forms an angle of repose to fill the exit port with the particulate material accumulating on that surface. The gap between the exit port and the surface of the pane facing the exit port may be configured such that in a second operating state, the particulate material forms an angle of repose to allow continuous flow of the particulate material through the exit port with the particulate material accumulating on that surface, e.g., and not fill the exit port. The first operating state may or may not comprise movement of the layer dispensing mechanism (including the material dispenser) along the target surface. In some embodiments, the second operating state comprises movement of the layer dispensing mechanism (including the material dispenser) along the target surface. In some embodiments, the agitation of the particulate material (e.g., using the agitator(s)) homogenizes the distribution of the particulate material along a direction (e.g., substantially) perpendicular to the direction of movement of the material dispenser. The homogenization of the particulate material may comprise distribution of their density and/or amount. The homogenization may occur (i) as the particulate material exits the exit port of the material dispenser and/or (ii) when the particulate material flow from the exit port towards edge(s) of the panel in the material fall, the agitator(s) may be configured to facilitate such homogenization. The configuration may comprise location relative to the panel and/or exit port, type of agitator(s) utilized, translation speed of the material dispenser, acceleration of the material dispenser, movement type (e.g., continuous or intermittent) of the material dispenser, or frequency of the agitation. At least two types of the agitators may be the same. At least two types of the agitators may be different. The particulate material may be powder composed of any material disclosed herein, e.g., comprising a ceramic, elemental carbon, an elemental metal or a metal alloy.

[0247] Fig. 22 depicts a vertical cross-sectional examples of a material dispensing mechanism comprising a panel. Material dispensing mechanism 2200 includes a reservoir 2202 configured to retain pre-transformed material 2204 within a volume of the reservoir 2202. The pre- transformed material can be a particulate material. Material dispensing mechanism 2200 includes an exit port 2206 having an FLS (e.g., a width 2208). Material dispensing mechanism includes a panel 2210 oriented with respect to the exit port 2206 such that a surface 2211 of the panel 2210 facing exit port 2206 is aligned perpendicularly along the z-axis 2212 with exit port 2206. Surface 2211 of panel 2210 is separated along z-axis 2212 from exit port 2206 by a gap 2214. Pre-transformed material 2204 exiting exit port 2206 rests on the surface 2211 of panel 2210 and forms a heap of pre-transformed material having an angle of repose 2216. Panel 2210 has a lateral dimension 2218, e.g., an FLS perpendicular to z-axis 2212. As depicted in the example of Fig. 22, the material dispensing mechanism 2200 is in a first operating state. For example, the first operating state comprises a “no flow” state where minimal (e.g., zero) material 2204 is flowing off an edge of panel 2210. For example, the first operating state comprises a lateral spread of pre-transformed material 2204 that is smaller (e.g., at least about the same or smaller) than a lateral dimension 2218 of panel 2210. The pre-transformed material 2204 has an angle of repose 2216. For example, the first operating state comprises particulate material that is not fluidized (e.g., static) with respect to the material dispensing mechanism 2200.

[0248] Fig. 22 depicts a vertical cross-sectional example of material dispensing mechanism 2250 that includes a reservoir 2252 configured to retain pre-transformed material 2254 within a volume of reservoir 2252. Material dispensing mechanism 2250 includes an exit port 2256 having an FLS (e.g., a width 2258). Material dispensing mechanism includes a panel 2260 oriented with respect to the exit port 2256 such that a surface 2261 of the panel 2260 is aligned perpendicularly along the z-axis 2262 with the exit port 2256. Surface 2261 of the panel 2260 is separated along z-axis 2262 from the exit port 2256 by a gap 2264. Pre-transformed material 2254 exiting the exit port 2256 rests on the surface 2261 of the panel 2260 and forming an angle of repose 2266. Panel 2260 has a lateral dimension 2268, e.g., an FLS perpendicular to z-axis 2262. As depicted in the example shown in Fig. 22, the material dispensing mechanism 2250 is in a second operating state. For example, the second operating state comprises a “flow” state where a flow (e.g., a material fall 2270) of pre-transformed material 2254 is flowing off one or more edge(s) 2272 of panel 2260. The second operating state comprises a lateral spread of pretransformed material 2254 that is larger (e.g., at least about the same or greater) than a lateral dimension 2268 of panel 2260 when the pre-transformed material 2254 has an angle of repose 2266, e.g., upon agitation of the pre-transformed material. For example, the second operating state comprises powder material that is fluidized with respect to the material dispensing mechanism 2250. The material dispenser mechanisms in examples 2250 and 2200 are depicted in relation to gravitational vector 2299 directed towards gravitational center G. The powder may flow from the material dispenser in one or more material falls. In some embodiments, as depicted in Fig. 22, powder flows from the material dispenser off a plurality of edges of the panel. In some embodiments, as depicted in Fig. 21 , powder flows from the material dispenser off one edge of the panel. [0249] In some embodiments, a material dispensing mechanism includes a panel having a lip or restricted edge configured to prevent a flow of pre-transformed material. An example of a lip is shown in Fig. 18, 1819. Fig. 23 depicts examples of a material dispensing mechanism, each comprising a panel. Material dispensing mechanism 2300 includes a reservoir 2302 configured to retain pre-transformed material 2304 within a volume of the reservoir 2302. Material dispensing mechanism 2300 includes an exit port 2306 having an FLS (e.g., a width 2308). Material dispensing mechanism includes a panel 2310 oriented with respect to the exit port 2306 such that a surface 2311 of the panel 2310 is faces the exit port and is aligned perpendicularly along the z-axis 2312 with the exit port 2306. Panel 2310 comprises a restrictor 2313 (e.g., a lip, an edge, a barrier, or the like) configured to restrict (e.g., prevent) a spread of pre-transformed material 2304 on a surface 2311 of the panel 2310. Surface 2311 of the panel 2310 is separated along z-axis 2312 from the exit port 2306 by a gap 2314. Pre-transformed material 2304 exiting the exit port 2306 rests on the surface 2311 of the panel 2310 and forms an angle of repose 2316, which pre-transformed material is a particulate material such as powder. Panel 2310 has a lateral dimension 2318, e.g., an FLS perpendicular to z-axis 2312. As depicted in the example shown in Fig. 23, the material dispensing mechanism 2300 is in a first operating state. For example, the first operating state comprises a “no flow” state where minimal (e.g., zero) material 2304 is flowing off an edge of the panel 2310. For example, the first operating state comprises a lateral spread of pre-transformed material 2304 in at least one direction parallel to surface 2311 of panel 2310 that is smaller (e.g., at least about the same or smaller) than a lateral dimension 2318 of the panel when the pre-transformed material 2304 has an angle of repose 2316. For example, the first operating state comprises pre-transformed material that is not fluidized (e.g., static) with respect to the material dispensing mechanism 2300.

[0250] Fig. 23 depicts an example material dispensing mechanism 2350 includes a reservoir 2352 configured to retain pre-transformed material 2354 within a volume of the reservoir 2352. Material dispensing mechanism 2350 includes an exit port 2356 having an FLS (e.g., a width 2358). Material dispensing mechanism includes a panel 2360 oriented with respect to the exit port 2356 such that a surface 2361 of the panel 2360 is aligned perpendicularly along the z-axis 2362 with the exit port 2356. Panel 2360 comprises a restrictor 2353 (e.g., a lip, an edge, a barrier, or the like) configured to restrict (e.g., prevent) a spread of pre-transformed 2354 in at least one direction on surface 2361 of the panel 2360. Surface 2361 of the panel 2360 is separated along z-axis 2362 from the exit port 2356 by a gap 2364. Pre-transformed material 2354 exiting the exit port 2356 rests on the surface 2361 of the panel 2360 and forming an angle of repose 2366. Panel 2360 has a lateral dimension 2368, e.g., an FLS perpendicular to z-axis 2362. As depicted in Fig. 23, the material dispensing mechanism 2350 is in a second operating state. For example, the second operating state comprises a “flow” state where a flow (e.g., a material fall 2370) of pre-transformed material 2354 is flowing off one or more edge(s) 2372 of the panel 2360 and restricted (e.g., prevented) from flowing off one or more edge(s) 2374 by the restrictor 2353. For example, the second operating state comprises a lateral spread of material 2354 that is larger (e.g., at least about the same or greater) than a lateral dimension 2368 of the panel 2360 when the material 2354 has an angle of repose 2366. For example, the second operating state comprises pre-transformed material that is fluidized with respect to the material dispensing mechanism 2350, e.g., using agitation. At times, as depicted in Fig. 23, pretransformed may flow off one edge 2372 of the panel 2360 and may not flow off another edge 2374 of the panel 2360 due to restrictor 2353. The material dispenser mechanisms in examples 2300 and 2350 are depicted in relation to gravitational vector 2399 directed towards gravitational center G.

[0251] At times, the material dispensing mechanism may comprise controller(s) of agitation. The controller(s) may comprise a passive controller or an active controller. For example, an active vibration controller, and/or a passive vibration controller. The passive agitation controller may comprise a mechanism configured to passively dampen the agitation, e.g., due to its shape and/or material properties. The agitation may comprise acoustic vibrations. The passive controller may comprise an acoustic black hole (abbreviated herein as “ABH”).

[0252] At times, the material dispensing mechanism comprises an absorber. One or more absorbers may be affixed to, or be part of, a panel of the material dispensing mechanism, e.g., may be affixed to a waveguide of the material dispensing mechanism. The absorber(s) may be affixed to the waveguide to minimize (e.g., prevent) standing wave(s) in the waveguide, e.g, when a transducer coupled to the waveguide induces vibrational motion in the waveguide. For example, absorber(s) may be affixed to the waveguide to reduced (e.g., eliminate) reflections of ultrasonic waves in the waveguide when vibrational motion is induced in the waveguide. Suppressing the standing wave in the waveguide can be defined as a low amplitude (e.g., zero) of reflections at an end of the waveguide, e.g., a standing wave ratio of about 1. The absorber(s) can comprise a dampening component. A dampening component can comprise (A) an absorptive material (e.g., comprising rubber, adhesive, elastomer, a viscoelastic solid, or powder), (B) a shape of the waveguide at one end (e.g., a curl or swirl-like shape, or a tapering shape), (C) rough surface of the waveguide, (D) a powder bucket or another absorptive load in contact with an end of the waveguide, (E) an acoustic black hole, (F) another feature that will slowly (e.g., gradually) dampen an acoustic wave at one end of the waveguide, or (G) any combination of (A)-(F). Dampening the acoustic wave comprises reducing the acoustic wave’s energy. Dampening the acoustic wave comprises reducing the acoustic wave’s amplitude and/or speed (e.g., frequency). For example, an absorber can be a swirl-like shape of an end of the waveguide that is in contact with an absorptive load (e.g., a powder bucket). The absorber(s) may be configured to gradually (e.g., over a length of the panel) absorb energy to (e.g., substantially) avoid creating a reflection at an end of the waveguide caused, e.g., by terminating the waveguide abruptly. As an acoustic wave travels within an ABH portion of the waveguide, the acoustic wave may decrease its amplitude and/or speed in a continuous manner, e.g., following a function such as a linear function.

[0253] Fig. 24 depicts a schematic example of various portions of a material dispensing mechanism. The material dispensing mechanism 2400 shown in perspective view, comprises a panel 2404 coupled to a transducer 2406. The transducer 2406 is coupled to the panel 2404 via coupler(s) 2408. A reservoir 2410 is aligned with respect to the panel 2404 such that an exit port of the reservoir 2410 is disposed facing a surface of the panel 2404 that is vertically separated from the exit port by a gap. Fig. 24 depicts a schematic example of a portion of a material dispensing mechanism 2420 shown as a portion of a vertical cross-section along sectional line AA while horizontally viewing into the dispenser. The material dispensing mechanism 2420 comprises a panel 2422. The panel is affixed to the material dispensing mechanism by a fixture 2424, e.g., an absorptive material. The material dispensing mechanism 2420 comprises sides 2426 of the body of the material dispenser, where an exit port 2428 is disposed facing a surface 2430 of the panel 2422. The surface 2430 is separated from a bottom of the reservoir 2426 by a gap 2432. Fig. 24 depicts a schematic example of a portion of a material dispensing mechanism 2440 shown as a portion of a vertical cross-section along sectional line BB while horizontally viewing into the dispenser. The material dispensing mechanism 2440 comprises a panel 2442. The panel is affixed to material dispensing mechanism by a fixture 2444, e.g., an absorptive material. The material dispensing mechanism 2440 comprises sides 2446 of the body of the material dispenser, where an exit port 2448 is disposed facing a surface 2450 of the panel 2442. The surface 2450 is separated from a bottom of the reservoir 2446 by a gap 2452. The material dispenser mechanisms and portions thereof in examples 2400, 2420, and 2440 are depicted in relation to gravitational vector 2499 directed towards gravitational center G.

[0254] At times, a material dispensing mechanism comprises a panel. The panel can comprise (e.g., can be) a waveguide, e.g., an ultrasonic waveguide, that is coupled to a transducer. The waveguide may include one or more support features for affixing the waveguide to the material dispensing mechanism. The support features may comprise suspension beams. In some embodiments, the support features may be points along the waveguide corresponding to null locations of a standing wave within the waveguide when the transducer is inducing vibrational motion in the waveguide. The support features may be points of mechanical support for the waveguide, e.g., to support the waveguide and (substantially) prevent warping/bowing of the waveguide along a length of the waveguide. The support features may be affixed to the material dispensing mechanism and configured to minimize an effect (e.g., substantially not dampen) on the vibrational motion of the waveguide. For example, the features may be suspension beams located along the waveguide at locations corresponding to quarter-wavelengths of a vibrational frequency induced in the waveguide by the transducer.

[0255] Fig. 25 is a schematic of an example waveguide comprising support features. Waveguide 2500 comprises a length 2502 and support features 2504. Support features 2504 may be oriented perpendicular to the length 2502 and located at null point(s) along the length 2502 of a standing wave induced in the waveguide 2500 by a transducer that are a distance 2506 apart. A dimension 2508 (e.g., a height) of the support features 2504 can be defined as height = (2n + 1) where A is a wavelength of the induced vibrational motion, and n can be any integer value.

[0256] At times, a material dispensing mechanism comprises an agitator coupled to a panel. The panel may be oriented with respect to an exit port of a reservoir of the material dispensing mechanism such that a surface of the panel is disposed facing towards the exit port. In some embodiments, the material dispenser, comprises an orifice, e.g., a nozzle. In some embodiments, the panel comprises an orifice, e.g., a nozzle. The nozzle may be any nozzle disclosed herein. The panel may comprise, or be operatively coupled to, a waveguide. The panel may be operatively coupled to, or comprise, an agitator. The orifice may be a precision orifice, e.g., an orifice that is not subject to assembly or adjustment variation. For example, the precision orifice can be a computer-numerical control (CNC) machined precision slot, hole(s), mesh, or the like. The orifice can be oriented with respect to the panel such that, (A) in a first operational state, an angle of repose of the particulate material disposed on a surface of the panel facing the exit port of the material dispenser, results in (e.g., substantial) retainment particulate material on the panel; and (B) in a second operational state, an angle of repose on that surface of the panel results in flow of the particulate material through the orifice, e.g., when particulate material is agitated such as by agitations induced by the agitator, e.g., by the waveguide that is the panel. The orifice can be oriented with respect to the panel such that, (A) in a first operational state, an angle of repose of the particulate material disposed on a surface of the panel facing the exit port of the material dispenser, does not result in substantial (e.g., zero) flow of particulate material through the orifice; and (B) in a second operational state, an angle of repose on that surface of the panel results in flow of particulate material through the orifice. E g., when vibrational motion is induced in the particulate material. For example, the orifice can be offset from a center point of the panel that overlaps with a center point of the exit port of the material dispenser. For example, the orifice can be offset along an XY plane parallel to a surface of the panel opposing the exit port of the material dispenser. The exit opening may be disposed asymmetrically with respect to the panel, and the orifice can be disposed symmetrically with respect to the panel, e.g., when viewing the panel horizontally. The exit opening may be disposed symmetrically with respect to the panel, and the office can be disposed asymmetrically with respect to the panel, e.g., when viewing the panel horizontally. For example, a location of the orifice can be selected, based at least in part on (A) an angle of repose of the particulate, (B) a dimension of a gap between a surface of the panel and the exit port of the reservoir along a z-axis (e.g., a gravitation axis) of the 3D printing system, (C) a temperature of an environment at which the material dispenser is disposed during its operation, (D) a pressure of the environment during operation, (E) a level of humidity of the environment during operation, or (F) any combination thereof. For example, the precision orifice may have an FLS of at most about 800 microns (pm), 700 pm, 500 pm, 400 pm, 300 pm, 200 pm, 100 pm, 50 pm, or less. For example, the precision orifice may have an FLS on the order of or smaller than an FLS of the exit port of the reservoir. For example, the precision orifice may have an FLS that is at least about an order of magnitude smaller than an FLS of the exit port of the material dispenser.

[0257] Fig. 26 depicts various schematic views of an example material dispensing mechanism. As depicted in Fig. 26, a vertical cross-sectional example of material dispensing mechanism 2600 that comprises an orifice 2602. Material dispensing mechanism 2600 comprises a body of reservoir 2604 and a panel 2606 oriented with respect to an exit port 2608 of the reservoir. The orifice 2602 is located at a distance from a center axis 2610 of the panel 2606 by an offset 2612. Panel 2606 comprises a restrictor 2614, e.g., an edge or a lip, on edge(s) of the panel 2606. Fig. 26 depicts an example material dispensing mechanism 2620 comprising a body of a reservoir 2624 and a panel 2626. Panel 2626 comprises an orifice 2622. Panel 2626 comprises a restrictor 2634, e.g., an edge or a lip, on edge(s) of the panel 2626. As depicted, reservoir body 2624 retains pre-transformed material that is a particulate material 2630, where a portion of the particulate material 2630 exits through exit port 2628 and forms an angle of response on a surface 2632 of panel 2626. For example, the angle of repose when the material dispensing mechanism 2620 is in a first operating state, e.g., when the pre-transformed material adjacent to the exit port 2628 and/or disposed on panel 2626 is not being agitated, e.g., by not agitating the panel 2626. A dimension 2639 of the lateral spread of the particulate material on surface 2632 from axis 2636 is less than a distance from the axis 2636 to the orifice 2622, e.g., offset 2638. Fig. 26 depicts an example material dispensing mechanism 2640 comprising a reservoir body 2644 and a panel 2646. Panel 2646 comprises an orifice 2642. Panel 2646 comprises a restrictor 2654, e.g., an edge or a lip, on edge(s) of the panel 2646. As depicted, reservoir body 2644 retains pre-transformed material (e.g., particulate material 2650), where a portion of particulate material 2650 exits through exit port 2628 and forms an angle of response on a surface 2652 of panel 2646. For example, the angle of repose when the material dispensing mechanism 2640 is in a second operating state, e.g., when the pre-transformed material adjacent to the exit port 2648 and/or disposed on panel 2646 is being agitated such as by agitating the panel. For example, when a transducer coupled to the panel 2646 induces vibrational motion in the panel 2646. A lateral spread of the particulate material on surface 2652 from axis 2656 is greater than a distance from the axis 2656 to the orifice 2642 such that a portion of the particulate material flows through the orifice 2642 by generated material fall 2651 . In the second operating state, e.g., when the particulate material 2650 is fluidized, the restrictor 2654 restricts (e.g., prevent) a flow of the particulate material 2650 over one or more edges of the panel 2646. For example, flow of particulate material may be restricted (e.g., substantially limited) to only through the orifice 2642. Fig. 26 depicts an example view (e.g., as viewed from a YZ plane) of a material dispensing mechanism 2660 comprising a panel 2662. As depicted, material dispensing mechanism 2660 comprises a reservoir 2664 where the panel 2662 is oriented at a bottom of the reservoir 2664. Fig. 26 depicts an example view (e.g., as viewed from an XY panel) of a bottom of the material dispensing mechanism 2680 comprising a panel 2682. As depicted, the orifice 2684 is offset from a symmetry element 2681 of the panel 2662. Symmetry element 2681 comprises a C2 axis or a mirror plane perpendicular to the page. Dotted rectangle 2683 represents location of the exit port of the material dispenser with which panel 2682 is aligned. In the example shown in 2680, the exit opening is disposed symmetrically with respect to the panel and the symmetry element 2681 , and the orifice is disposed asymmetrically with respect to the panel and with respect to symmetry element 2681 . The material dispenser mechanisms in examples 2600, 2620, 2640, and 2660 are depicted in relation to gravitational vector 2699 directed towards gravitational center G. The axis Z in the cartesian coordinates of Fig. 26 is directed in an opposite direction to gravitational vector 2699.

[0258] At times, a material dispensing mechanism comprises a first panel and a second panel. The first panel may comprise an orifice, e.g., as disclosed herein. The first panel may be oriented with respect to an exit port of a reservoir of the material dispensing mechanism such that an exit port of the reservoir is aligned with respect to the orifice of the first panel along a z- axis (e.g., along a gravitational vector pointing towards the gravitational center). For example, a center point of the exit port of the reservoir may or may not be aligned with a center point of the orifice of the first panel. The center point may the same or may be different from a center of the FLS of the exit port and orifice respectfully. The first panel may be coupled to a transducer such that the transducer may induce vibrational motion in the first panel, e.g., as a waveguide. The first panel may be affixed to the material dispensing mechanism by an absorptive material, e.g., a high impedance mismatched material. The material dispensing mechanism may comprise a second panel. The second panel may be a gate, shutter, flapper, iris, or another component configured to block at least a portion (e.g., all) of an orifice on the first panel such that the pretransformed material may not be able to flow to the target surface such as the exposed surface of the material bed. The second panel may be located between an orifice of the first panel and the exposed surface of the material bed. The second panel (e.g., a mechanical gate), may hinder (e.g., prevent) a flow of particulate material from the reservoir to the target surface. For example, the second panel may hinder (e.g., prevent) a flow of particulate material from the reservoir to the target surface when the first panel is in (A) a first operating state (e.g., a vibrational motion is being induced), (B) a second operating state (e.g., no vibrational motion is being induced), or (C) a combination thereof. A dimension of the second panel may be selected based at least in part on (A) a distance between the second panel and the orifice of the first panel, (B) an angle of repose of particulate material, or (C) a combination thereof. In some instances, pre-transformed material (e.g., particulate material) may be retained within the reservoir of the material dispensing mechanism. The second panel may have a plurality of states, for example, (A) an “open”, “ON,” or “flow” state where particulate material flows from the reservoir to the target surface, (B) a “closed, “OFF”, or “no flow” state where particulate material is restricted (e.g., prevented) from flowing from the reservoir to the target surface, or (C) another intermediate state (e.g., a partial or restricted flow state). Particulate material may be disposed on a surface of the second panel, for example, when the second panel is in an “OFF” state. The particulate material disposed on the surface of the second panel may be maintained on the surface of the panel by an angle of repose of the particulate material such that minimal (e.g., zero) particulate material flows off an edge of the second panel towards the target surface. The second panel may be actuated, e.g., mechanically actuated, to expose the orifice of the first panel to the exposed surface of the material bed. In some embodiments, the second panel may be actuated (e.g., opened) to expose the orifice of the first panel to the target surface while vibrational motion is induced in the first panel, e.g., to fluidize the particulate material in the “ON” state. In some embodiments, the material dispensing mechanism comprises a third panel, e.g., where the second panel and the third panel are shutters configured to open and close. In some embodiments, the second panel may be actuated, and vibrational motion induced in the first panel to fluidize the particulate material until the reservoir becomes empty (e.g., substantially empty) of particulate material, or has sufficient material to retain an angle of repose that will cause the exit port of the material dispenser to close by the accumulation of particles on the first panel. In some embodiments, the second panel may selectively actuate in combination with fluidization of the particulate material via induced vibrations in the first panel for a period of time to deposit an amount of particulate material on the target surface (e.g., to deposit one layer).

[0259] Fig. 27 depicts various schematic views of an example material dispensing mechanism. Material dispensing mechanism 2700 comprises a reservoir 2702 and a first panel 2704 affixed to the material dispensing mechanism by fixture 2706. Fixture 2706 may comprise a flexible or rigid material configured to retain the first panel by a fixed distance from an exit port of the reservoir. For example, fixture 2706 may be an absorptive material, e.g., an elastomer, glue, rubber, or the like. For example, fixture 2706 may be a rigid clamp to retain the first panel at a fixed distance from the exit port of the reservoir, e.g., a described with reference to Fig. 25. First panel 2704 comprises an orifice 2708. As depicted in the example show in Fig. 27, orifice 2708 is aligned with respect to exit port 2710 of reservoir body 2702 along a z-axis 2712. The material dispensing mechanism 2700 further comprises a second panel 2714, e.g., a physical shutter such as a mechanical shutter. Although depicted in Fig. 27 as a lateral motion along an XY panel, the second panel may be moveable in any other direction, e.g., swing outward towards a z-axis, rotational motion about the XY panel, or the like. Second panel 2714 is aligned with exit port 2710 and orifice 2708 about z-axis 2712. Fig. 27 depicts an example material dispensing mechanism 2730 comprising a reservoir body 2732 and a first panel 2734 affixed to the material dispensing mechanism by fixture 2736. Reservoir 2732 retains pre-transformed material, e.g., particulate material 2733. A portion of particulate material 2746 is disposed on a surface of a second panel 2744, e.g., exits opening 2740 and through orifice 2738. The particulate material disposed on the surface of the second panel 2744 may be maintained on the surface of the second panel by an angle of repose of the particulate material such that minimal (e.g., zero) particulate material flows off an edge of the second panel towards the exposed surface of the material bed. As depicted in Fig. 27, material dispensing mechanism 2730 is in an “OFF” state where minimal (e.g., zero) particulate material flows from the material dispensing mechanism 2730 from the second panel 2744, e.g., towards a target surface such as an exposed surface of the material bed. Fig. 27 depicts an example material dispensing mechanism 2760 comprising a reservoir body 2762 and a first panel 2764 affixed to the material dispensing mechanism by fixture 2766. Reservoir body 2762 retains pre-transformed material in its interior space, e.g., retain a particulate material 2763. Particulate material 2763 is fluidized and forms a material fall 2776 flowing out of the reservoir 2762 through exit port 2770 and through orifice 2768 of the first panel 2764. As depicted, material dispensing mechanism 2760 is in an “ON” state comprising a material fall 2776, e.g., a flow of particulate material. Second panel 2774, e.g., a physical closure such as a physical shutter, is in an “open" state exposing the material fall 2774 to an exposed surface of a material bed. A transducer coupled to first panel 2764 may induce vibrational motion (e.g., ultrasonic vibration) in the first panel which can fluidize the particulate material 2763 to cause a flow of particulate material out of the reservoir 2762. The material dispensing mechanisms in examples 2700, 2730, and 2760 are depicted in relation to gravitational vector 2799 directed towards gravitational center G. The gravitational center is of an environment in which the material dispensers are disposed in, e.g., the gravitational center of Earth.

[0260] In some embodiments, the layer removal mechanism comprises a material remover. At times, e.g., as depicted in Fig, 28, layer removal mechanism 2800 comprises a material reservoir 2807 and a material attraction portion in which material is attracted into a portion of the body of the removal mechanism 2804. The material removal mechanism may be operatively coupled to an attractive force, e.g., a vacuum, electric, or magnetic force source. For example, the material removal mechanism may be operatively coupled to a vacuum pump. The material removal mechanism may be a suction (vacuum) device. A first layer of a first thickness is deposited on a material bed. The first layer may also be deposited or on a platform, e.g., by any material dispensing mechanism disclosed herein. A material removal mechanism may translate along direction (e.g., about an XY plane, movement in X, Y, and Z Cartesian coordinate system) and can be used to remove a portion of the first layer to form a second layer having a second thickness that is thinner than the first thickness of the first layer and having an exposed planarized surface. The material removal mechanism may comprise a nozzle having an entrance port through which particulate material enters the removal device from the top surface of the material bed. Fig. 28 shows an example of material removal mechanism 2800 having an entrance port 2812 of nozzle 2804. Material is attracted from material bed having starting material 2810 deposited at a thickness 2809 on base 2811. The material remover translates in a direction 2802 and attracts a portion of starting material 2810 into its body. The attracted starting material 2805 enters nozzle 2804 through entrance port 2812 and is diverted 2806 into an internal reservoir 2807. Fig. 28 is depicted relative to gravitational vector 2899 directed towards gravitational center G. The entrance cavity to which the particulate material enters the suction device (e.g., FIG. 28, 2805) can be of any shape. The particulate material removal mechanism (e.g., suction device) may include one or more suction nozzles. The suction nozzle may comprise any of the nozzles described herein. The nozzles may comprise of a single opening or a multiplicity of openings as described herein. The openings may be vertically leveled or not leveled). The openings may be vertically aligned, or misaligned. In some examples, at least two of the multiplicity of openings may be misaligned. The multiplicity suction nozzles may be aligned at the same height relative to the substrate (e.g., FIG. 28, 2811), or at different heights (e.g., vertical height). The different height nozzles may form a pattern or may be randomly situated in the suction device. The nozzles may be of one type, or of different types. The particulate material removal mechanism (e.g., suction device) may comprise a curved surface, for example adjacent to the side of a nozzle. Particulate material that enters through the nozzle may be collected at the curved surface. The nozzle may comprise a cone. The cone may be a converging cone or a diverging cone. The particulate material removal mechanism (e.g., suction device) may comprise a particulate material reservoir. The particulate material that enters the particulate material removal mechanism (e.g., 2805) may at times enter the particulate material removal mechanism reservoir. The reservoir can be emptied after each particulate material layer has been leveled, when it is filled up, at the end of the build cycle, or at a whim. The reservoir can be continuously emptied during the operation of the particulate material removal mechanism. At times, the particulate material removal mechanism does not have a reservoir. At times, the particulate material removal mechanism constitutes a particulate material removal (e.g., a suction) channel that leads to an external reservoir. The particulate material removal mechanism may comprise an internal reservoir.

[0261] At times, layer dispensing mechanism comprises a material dispensing mechanism and a planarizing mechanism. The planarizing mechanism may be a particulate material removal mechanism, for example, a roller device. The roller may be coupled to a control system. The control system may control the rate of rotations of the cylinder and/or the rate of its lateral (e.g., along a material bed), horizontal or angular movement.

[0262] The roller may comprise a smooth surface, a rough surface, an indentation, a depression, or a cavity. The roller may be any of the rollers disclosed herein. Fig. 29 depicts a schematic example of a planarization component of a layer dispensing mechanism for removing a portion of a deposited layer. For example, a first layer of a first thickness 2909 is deposited on a material bed 2910 or on a platform 2911 . Fig. 29 shows a leveling mechanism (e.g., a roller) used to remove a portion of the first layer to form a second layer having a second thickness 2908 that is thinner than the first thickness 2909 of the first layer. Fig. 29, 2904 and 2905 shows examples of various alternative rollers described herein. The roller of the leveling mechanism may at times rotate in the direction of lateral movement of the leveling mechanism, or in a direction opposite of the direction of lateral movement of the leveling mechanism. FIG. 29, 2901 shows examples of the lateral movement direction of roller 2903. In this example, roller 2903 rotates opposite to the direction of movement of the planarizing mechanism, along an axis that is both the long axis of the roller and normal to the lateral direction of the movement of the roller (2901). When the roller revolves (rotates), it may induce movement of any atmosphere surrounding the roller that causes the particulate material to become airborne and depart from the exposed surface of the material bed. Thus the particulate material can be pushed away from the material bed. FIG. 29, 2907 shows examples of the movement of atmosphere surrounding the roller in relation to gravitational vector 2999 directed towards gravitational center G. The roller may be situated at a first distance above the surface of the layer of particulate material. [0263] In some embodiments, the material dispensing mechanism comprises an agitator. The agitator may comprise a waveguide. In some embodiments, the waveguide may be a multimode waveguide or a single mode waveguide. In some embodiments, the material dispensing mechanism utilizes a single mode waveguide, e.g., by including an outer member (e.g., tube). The tube may be a perforated tube or a non-perforated tube. The perforated tube may facilitate inflow and outflow of the particulate material. At times, the outer member is configured to be disposed around an optional inner member disposed in the outer member. The (elongated) lengths of the inner member and outer member may be (e.g., substantially) the same. The outer member (also referred here as a hollow member) may propagate through a direction in which a change in the level of the material is experienced over time (e.g., filling and/or emptying). The waveguide may or may not include the inner member (e.g., be devoid of an inner member). The waveguide may comprise (e.g., only) an outer member that is hollow. The outer hollow member (e.g., casing) may or may not be permeable (e.g., to the material whose level in the container is of interest). In some embodiments, the hollow (outer) member is permeable. The permeable hollow member may be configured to facilitate permeation of the material (e.g., particulate material such as powder) that is subject to the level measurement. The permeable hollow member may comprise open holes that may (e.g., substantially) retain confinement of the electromagnetic wave guided by the waveguide, or have a minimum reduction in intensity of the electromagnetic wave in the waveguide. In some embodiments, the waveguide includes a permeable hollow member that comprises open pores facilitating equilibration of particulate material level (and of the container atmosphere) between the interior (e.g., gap) space in the waveguide, and the level of the particulate material in the container external to the waveguide (e.g., as delineated herein).

[0264] In some embodiments, the waveguide is a single mode waveguide. The elongated direction of the waveguide may be disposed at the direction of change in material (i) filling up a container (e.g., vertically), and/or (ii) being removed from the container. The material may be attracted by gravity to the bottom of the container. The waveguide may be vertically aligned in the container along the gravitational vector directed towards the gravitational center. The atmosphere of the container can be any atmosphere disclosed herein.

[0265] In some embodiments, the waveguide of comprises a hollow member. The hollow member may or may not be permeable to gas, liquid, and/or particulate matter. In some examples, the hollow member is permeable. The hollow member may encase the internal member of the waveguide while forming a gap between the casing and the internal member. The hollow member may allow (e.g., substantial) entrapment of the electromagnetic wave in the internal volume of the waveguide (e.g., the gap), and facilitate material (e.g., gas, liquid, and/or particulate matter) to ingress (e.g., and egress) through the hollow member. The hollow member (e.g., casing) of the waveguide may be elongated in one direction and have a cross section in a normal direction to the one direction. The cross section of the hollow member may comprise a geometric shape. The geometric shape of the hollow member cross section may comprise an ellipse (e.g., circle), or a polygon. The polygon may comprise a rectangle (e.g., square). The geometric shape may be configured to support propagation of the electromagnetic waves in the gap from one end of the waveguide towards its opposite end. For example, the hollow member may comprise an elongated column or a box. When a metallic inner member of the waveguide contacts a metallic hollow member, they may form a shorted circuit (e.g., for the electromagnetic wave). The hollow member (e.g, casing) may enclose the inner member such that the hollow member does not contact the inner member. There may be a space between the hollow member and the inner member that forms a gap in which the electromagnetic waves propagate. The inner member may be disposed concentrically with its hollow member (e.g., casing). The inner member and its encasing hollow member may have the same, or a different cross, section (e.g., normal to the elongated direction of the waveguide). For example, the inner member may have a circular cross section while the hollow member (e.g., casing) may have a square cross section. For example, the inner member may have a circular cross section and the hollow member may have a circular cross section. The hollow member may be separated from the inner member by a gap. The gap may be structured by one or more spacers (e.g., O-rings) disposed between the inner member and the hollow member, e.g., at opposing ends of the waveguide’s elongation direction. The spacer(s) may be aligners. The spacer(s) may be configured to align the inner member with the hollow member (e.g., with the casing). The spacer(s) may comprise a non-conductive material (e.g., polymer such as a flexible polymer, or a cloth such as a flexible cloth). The spacer material may comprise a polymer (e.g., carbon or silicon based), a cloth (e.g., synthetic and/or non-synthetic), fiber glass, ceramic, or an allotrope of elemental carbon. The spacer comprise asbestos. The spacer may comprise Teflon. In some embodiments, at least a portion of the waveguide (e.g. its top and/or bottom portions with respect to the gravitational center) may comprise a non-conductive coating (e.g., having any of the spacer material disclosed herein). In some embodiments, at least a portion of the hollow member (e.g. its top and/or bottom portions with respect to the gravitational center) may comprise a non-conductive coating (e.g., having any of the spacer material disclosed herein). The coating may form a spacer between the hollow member (e.g., casing) and the inner member. The spacer may comprise, or be devoid of, an adhesive (e.g., glue). The spacer may contract the inner member and/or the hollow outer member (e.g., the casing). The waveguide may be configured to fit into a container and be positioned (i) in a direction of change of the material whose level in the container is of interest and/or (ii) in a manner that allows measuring an interface between a material of interest and a second material (e.g. atmosphere of the container) disposed in the container. The waveguide may be inserted into a cavity of the material dispenser, e.g., such that the waveguide may be surrounded at least in part by the particulate material in the cavity, e.g., when it contains particulate material. The waveguide may assist in measuring a level of the particulate material in the cavity. The waveguide may assist in vibrating the particulate material in the cavity.

[0266] In some embodiments, the material removal mechanism can be configured to create a flow of gas and/or material above a target surface (e.g., exposed surface of a material bed) that is sufficient to attract and/or reduce an amount of debris from the target surface. Sufficient to reduce an amount of debris may comprise sufficiently chaotic flow to reduce an amount of debris. The debris may comprise a hardened (e.g., transformed) or partially hardened (e.g., partially transformed) material. The debris may comprise (e.g., non-requested) spattered and/or splashed material resulting from the 3D printing. The debris may comprise soot generated as a result of the 3D printing. The debris may be a byproduct of the 3D printing.

[0267] In some embodiments, the layer dispensing mechanism comprises a material dispensing mechanism and a material remover. The layer dispensing mechanism may deposit a (e.g., substantially) planarized layer on an exposed surface of a material bed, e.g., where the exposed surface comprises 3D objects protruding from the exposed surface. The planarized layer deposited on the exposed surface may be thinner than a height of the protrusion of the 3D object(s). At times, a first layer may be deposited by a material dispensing mechanism having a first central tendency of planarity and a second central tendency of thickness. A portion of the first layer may be removed by a material remover to yield a second layer having a third central tendency of planarity and a fourth central tendency of thickness.

[0268] FIG. 30 shows examples of various stages of a layering method described herein. Fig. 30 shows an example 3000 of a material bed 3001 in which a 3D object 3003 is suspended in the material bed (e.g., comprising a pre-transformed material (e.g., particulate material)) between layering procedures of a 3D printing operation. Fig. 30 shows an example of energy beam 3007 projected onto the material bed to print 3D object 3003 that protrudes by vertical height 3005 from the exposed surface 3004 of material bed 3001 disposed on a base or on a platform 3002. The protrusion may be caused by deformation, e.g., warping caused upon hardening the 3D object 3003. Examples 3000, 3040, 3020, and 3060 are depicted in relation to gravitational vector 3099 directed towards gravitational center G. One or more energy beams can be used to transform at least a portion of the material bed (e.g., a layer (e.g., first layer) of pre-transformed material) to form at least a portion of the 3D object. The energy beam(s) can be directed to a target surface, e.g., surfaces of the pre-transformed material, exposed surface of the material bed, and/or a surface of the 3D object. Before and/or after the energy beam(s) is applied, an exposed (e.g., top) surface (e.g., 3004) of the material bed can optionally have a (e.g., substantially) planar surface. Any suitable leveling technique can be used. In some embodiments, a material removal mechanism is used, e.g., as described herein. In some cases, the leveling involves agitating the pre-transformed material to facilitate its deposition, e.g., using vibrations. The energy beam(s) can impinge on the exposed surface of the material bed to transform a portion (e.g., a portion of a layer) of pre-transformed material to form a portion (e.g., corresponding layer) of transformed (e.g., hardened) material as part of the 3D object.

Sometimes, the transformation process can cause debris to form on and/or within the material bed and/or the 3D object. For example, an energy of the energy beam(s) may be sufficiently energetic to eject pre-transformed, transformed, and/or transforming material from the target surface and land (splatters) on surrounding regions of the material bed and/or 3D object. The debris can correspond to transformed (e.g., hardened) material, partially transformed (e.g., partially hardened) material, contaminants (e.g., soot), or any combination thereof. The debris can correspond to agglomerated, sintered and/or fused pre-transformed particles (e.g, particulate). The debris particles can have any suitable shape and size. The debris particles can have regular and/or irregular (non-symmetric) shapes. For example, the debris particles can have globular (e.g., spherical, or non-spherical) shapes. The debris particles can be smaller (e.g., have smaller FLS) than the 3D object. The debris may have a FLS that is smaller and/or larger than the average FLS of the pre-transformed material (e.g., in case of a particulate material). For example, the debris particles can be larger (e.g., have larger FLS) than the pretransformed particles, as described herein. Larger can be by at least two times the FLS of the pre-transformed material particles. The debris particles can be smaller (e.g., have smaller crosssections (e.g., diameters)) than a height of a layer (e.g., first layer) of pre-transformed material, as described herein. In some cases, the debris particles have an average FLS (e.g., crosssection widths (e.g., diameters) (e.g., median cross-section widths)) of at least about 50 pm, 80 pm, 100 pm, 110 pm, 120 pm, 130 pm, 140 pm, 150 pm, 200 pm, 250 pm, 300 pm, 400 pm, 500 pm, 800 pm, 1000 pm, or 2000 pm. The debris particles can have a FLS ranging between any of those listed above (e.g., from about 50 pm to about 2000 pm, from about 50 pm to about 250 pm, or from about 250 pm to about 2000 pm). Sometimes, the debris interferes with subsequent formation of the 3D object. For example, the debris may cause defects (e.g., voids, inconsistencies, and/or surface roughness) in a subsequently formed portion (e.g., subsequent layer(s)) of the 3D object. [0269] Fig. 30 shows an example 3020 of a succeeding operation to 3000, where a layer having a first thickness (e.g., height) 3026 (also referred to as an additional layer, new layer or a second layer) is deposited on an exposed surface 3024 of the material bed 3021 , e.g., above the planar surface 3004 corresponding to the previous exposed surface of the material bed. Any suitable material deposition process can be used. In some embodiments, a material dispensing mechanism (e.g., material dispenser), as described herein, is used. The material dispensing mechanism can utilize gravitational force and/or gas flow (e.g., airflow) that also displaces (e.g., partially levels) the newly added material. The additional layer can be deposited such that a least a portion of the 3D object 3023 is exposed. In some embodiments, the additional layer does not have a leveled top surface, has a lower level of planarity as compared to a requested level of planarity, or has a higher level of roughness as compared to a requested level of roughness.

[0270] Fig. 30 shows an example 3040 of a succeeding material removal operation to 3020 where a portion of the additional layer is being removed from exposed surface 3044 of the material bed 3041 . As depicted in the example shown in Fig. 30, the material remover 3049 does not contact the additional layer, rather, it hovers above the additional layer. The material remover portions 3049 forming entrance port 3048 provides an attractive force by an attractive force source, e.g., a vacuum source (not shown). The attractive force causes flow along broken lines such as line 3042. Portions 3049 designate two wall portions of a vertical cross section of a dispenser body or a nozzle, leading to entrance port 3048. The attractive force creates an attractive flow along flow lines such as 3042 (e.g., comprising a vertical flow component) within the material bed 3041 and/or surrounding gas proximate to the material remover portion 3049. The attractive flow causes a portion of the material to be removed from the material bed 3041 and into the material remover 3049 (e.g., nozzle) as the material remover having portion 3049 translates along direction 3047, e.g., laterally about the XY plane. The material remover can translate in an opposite direction to direction 3047. Material remover reduces a first thickness 3026 of the deposited layer to a second thickness 3066 smaller than the first thickness. The removed material can be recycled using a recycling system, e.g., as described herein. For example, the material removal mechanism can be operationally coupled to the recycling system. The removed material can be directed to the recycling system via the material removal mechanism. The attractive force can be any suitable type of attractive force, e.g., as described herein. The debris can become entrained within the attractive flow and into the material removal mechanism, thereby removing at least a portion of the debris from the material bed (e.g., from the exposed surface thereof). This removal of at least a portion of the debris can reduce an occurrence of defects in and/or on the 3D object (e.g., final 3D object). The at least a portion of the debris may comprise at least about 70%, 80%, 90% of the debris deposited on the material bed. In some cases where the removed material is recycled by a recycling system. The recycling system can filter out at least some of the debris (e.g., using one or more filters, e.g., sieves) such that the recycled material can (e.g., substantially) include pre-transformed material (e.g., and used in subsequent layer forming operations).

[0271] During the layer deposition and/or 3D printing, the material bed may comprise a flowable material, and/or non-compressible material. During the 3D printing, the material bed may be (e.g., substantially) devoid of pressure gradients.

[0272] In some embodiments, a material removal mechanism removes material to form an exposed surface having a lower roughness, or a higher level of planarity, as compared to the one generated by the material dispensing mechanism. Fig. 30 shows an example 3060 of the additional layer after the material removal process. The additional layer having a second thickness (e.g., height) 3066 disposed on the exposed surface 3064 of the material bed 3061 can have a central tendency of thickness that is less than a maximal height (e.g., a vertical height) of protrusion 3063 of the 3D object 3063 such that a protrusion 3063 extends above the new exposed surface 3065 of the additional layer of thickness (e.g., height) 3066. The layer having first thickness 3026 has an exposed surface 3027 that is rougher than exposed surface 3065 of the layer having the second thickness 3066. The exposed surface 3027 having the first planarity (or first roughness) is generated by the dispenser, and the exposed surface 3065 having the second planarity (or second roughness) is generated by the remover. In some embodiments, the material removal mechanism can remove at least about 70%, 80%, 90%, 95%, 97%, 98%, 99%, 99.5%, 99.8% or 99.9% of the deposited material (e.g., the material deposited in example 3000) the percentages may designate weight percentages or volume percentages. In some embodiments, the percentages are calculated volume per volume. The new exposed surface can be (e.g., substantially) planar. The material removal operation may or may not expose a portion (e.g., a protruding portion such as 3061) of the 3D object. The thickness of the additional layer after the material removal (e.g., prior to a subsequent transformation operation) can vary depending on process requirements and/or system limitations. In some embodiments, a (e.g., average) thickness of the additional layer can be at least about 5 pm, 10 pm, 50 pm, 100 pm, 150 pm, 200 pm, 250 pm, 300 pm, 350 pm, 400 pm, 450 pm, or 500 pm. The average thickness of the leveled additional layer can be at most about 700 pm, 500 pm, 450 pm, 400 pm, 350 pm, 300 pm, 250 pm, 200 pm, 150 pm, 100 pm, 50 pm, 10 pm, or 5 pm. The (e.g., average) thickness of the leveled additional layer can be between any of the afore-mentioned (e.g., average) thickness values. For example, the (e.g., average) thickness can be from about 5 pm to about 500 pm, from about 10 pm to about 100 pm, from about 20 pm to about 300 pm, or from about 25 pm to about 250 pm. After the additional layer is complete, another transformation operation can be performed (e.g., using an energy beam (e.g., example 3000, energy beam 3007)) to form another layer of the 3D object. The sequences described with respect to the examples of Fig. 30 can be subsequently until the 3D object is complete. [0273] In some embodiments, the generated 3D object has a surface roughness profile. The generated 3D object can have various surface roughness profiles, which may be suitable for various applications. The surface roughness may be the deviations in the direction of the normal vector of a real surface from its ideal form. The generated 3D object can have a Ra value of as disclosed herein.

[0274] At times, the generated 3D object (e.g., the hardened cover) is substantially smooth. The generated 3D object may have a deviation from an ideal planar surface (e.g., atomically flat or molecularly flat) of at most about 1 .5 nanometers (nm), 2 nm, 3 nm, 4 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 100 nm, 300 nm, 500 nm, 1 micrometer (pm), 1.5 pm, 2 pm, 3 pm, 4 pm, 5 pm, 10 pm, 15 pm, 20 pm, 25 pm, 30 pm, 35 pm, 100 pm, 300 pm, 500 pm, or less. The generated 3D object may have a deviation from an ideal planar surface of at least about 1.5 nanometers (nm), 2 nm, 3 nm, 4 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 100 nm, 300 nm, 500 nm, 1 micrometer (pm), 1.5 pm, 2 pm, 3 pm, 4 pm, 5 pm, 10 pm, 15 pm, 20 pm, 25 pm, 30 pm, 35 pm, 100 pm, 300 pm, 500 pm, or more. The generated 3D object may have a deviation from an ideal planar surface between any of the afore-mentioned deviation values. The generated 3D object may comprise a pore. The generated 3D object may comprise pores. The pores may be of an average FLS (diameter or diameter equivalent in case the pores are not spherical) of at most about 1.5 nanometers (nm), 2nm, 3nm, 4nm, 5 nm, 10nm, 15nm, 20nm, 25nm, 30nm 35nm, 100nm, 300nm, 500nm, 1 micrometer (pm), 1 .5 pm, 2 pm, 3 pm, 4 pm, 5 pm, 10 pm, 15 pm, or 20 pm. The pores may be of an average FLS of at least about 1.5 nanometers (nm), 2nm, 3nm, 4nm, 5 nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 100nm, 300nm, 500nm, 1 micrometer (pm), 1 .5 pm, 2 pm, 3 pm, 4 pm, 5 pm, 10 pm, 15 pm, or 20 pm. The pores may be of an average FLS between any of the afore-mentioned FLS values (e.g., from about 1 nm to about 20 pm). The 3D object (or at least a layer thereof) may have a porosity of at most about 0.05 percent (%), 0.1% 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1 %, 2 %, 3 %, 4 %, 5 %, 6 %, 7 %, 8 %, 9%, 10 %, 20%, 30%, 40%, 50%, 60%, 70%, or 80%. The 3D object (or at least a layer thereof) may have a porosity of at least about 0.05 %, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1 %, 2 %, 3 %, 4 %, 5 %, 6 %, 7 %, 8 %, 9%, 10 %, 20%, 30%, 40%, 50%, 60%, 70%, or 80%. The 3D object (or at least a layer thereof) may have porosity between any of the afore-mentioned porosity percentages (e.g., from about 0.05% to about 80%, from about 0.05% to about 40%, from about 10% to about 40%, or from about 40% to about 90%). In some instances, a pore may traverse the generated 3D object. For example, the pore may start at a face of the 3D object and end at the opposing face of the 3D object. The pore may comprise a passageway extending from one face of the 3D object and ending on the opposing face of that 3D object. In some instances, the pore may not traverse the generated 3D object. The pore may form a cavity in the generated 3D object. The pore may form a cavity on a face of the generated 3D object. For example, pore may start on a face of the plane and not extend to the opposing face of that 3D object. [0275] The resolution of the printed 3D object may be at least about 1 micrometer, 1 .3 micrometers (pm), 1 .5 pm, 1.8 pm, 1 .9 pm, 2.0 pm, 2.2 pm, 2.4 pm, 2.5 pm, 2.6 pm, 2.7 pm, 3 pm, 4 pm, 5 pm, 10 pm, 20 pm, 30 pm, 40 pm, 50 pm, 60 pm, 70 pm, 80 pm, 90 pm, 100 pm, 200 pm, or more. The resolution of the printed 3D object may be at most about 1 micrometer, 1.3 micrometers (pm), 1.5 pm, 1.8 pm, 1.9 pm, 2.0 pm, 2.2 pm, 2.4 pm, 2.5 pm, 2.6 pm, 2.7 pm, 3 pm, 4 pm, 5 pm, 10 pm, 20 pm, 30 pm, 40 pm, 50 pm, 60 pm, 70 pm, 80 pm, 90 pm, 100 pm, 200 pm, or less. The resolution of the printed 3D object may be any value between the above- mentioned resolution values. At times, the 3D object may have a material density of at least about 99.9%, 99.8%, 99.7%, 99.6%, 99.5%, 99.4%, 99.3%, 99.2% 99.1%, 99%, 98%, 96%, 95%, 94%, 93%, 92%, 91%, 90%, 8%, or 70%. At times, the 3D object may have a material density of at most about 99.5%, 99%, 98%, 96%, 95%, 94%, 93%, 92%, 91%, 90%, 8%, or 70%. At times, the 3D object may have a material density between the afore-mentioned material densities. The resolution of the 3D object may be at least about 100 dots per inch (dpi), 300dpi, 600dpi, 1200dpi, 2400dpi, 3600dpi, or 4800dpi. The resolution of the 3D object may be at most about 100 dpi, 300dpi, 600dpi, 1200dpi, 2400dpi, 3600dpi, or 4800dip. The resolution of the 3D object may be any value between the afore-mentioned values (e.g., from 100dpi to 4800dpi, from 300dpi to 2400dpi, or from 600dpi to 4800dpi). The height uniformity (e.g., deviation from average surface height) of a planar surface of the 3D object may be at least about 100 pm, 90 pm, 80 pm, 70 pm, 60 pm, 50 pm, 40 pm, 30 pm, 20 pm, 10 pm, or 5 pm. The height uniformity of the planar surface may be at most about 100 pm, 90 pm, 80 pm, 70 pm, 60 pm, 50 pm, 40 pm, 30 pm, 20 pm, 10 pm, or 5 pm. The height uniformity of the planar surface of the 3D object may be any value between the afore-mentioned height deviation values (e.g., from about 100 pm to about 5 pm, from about 50 pm to about 5 pm, from about 30 pm to about 5 pm, or from about 20 pm to about 5 pm). The height uniformity may comprise high precision uniformity.

[0276] Fig. 31 is a flow diagram of an example process for generating a planar layer of powder material. At least a first portion of powder material is dispensed through an exit port of a material dispenser for generating a first layer having a first exposed surface that is substantially planar according to a first central tendency of planarity, the first exposed surface having a second central tendency of thickness of the first layer, the material dispenser comprising (I) the exit port and (II) a reservoir configured to accommodate powder material, the dispensing comprises inducing an increase of a flow rate of the powder material from the exit port of the material dispenser towards a target surface at least in part by using an agitator that is operatively coupled to, or is part of, the material dispenser (shown in block 3110). The material dispenser may translate with respect to a target surface to deposit the first portion of powder material.

[0277] Optionally, the target surface includes one or more protrusions from the target surface, the one or more protrusions being of one or more three-dimensional objects, and wherein the second central tendency of the thickness of the first layer is smaller than a maximal height (e.g., vertical distance) of the one or more protrusions from the target surface (shown in block 3120). The target surface can include a protrusion (e.g., protrusion 3063) has a maximal height that is larger than a thickness of a first layer (e.g., Fig. 30, first layer having a first thickness 3026 and having first exposed surface 3027).

[0278] Optionally, the method further comprises removing a second portion of powder material from the first layer for generating a second layer of powder material having a second exposed surface that is substantially planar according to a third central tendency of planarity, the third central tendency of planarity being of the same type as the first central tendency of planarity, and wherein the third central tendency of planarity is smaller than the first central tendency of planarity of the first layer such that the third central tendency of planarity is indicative of a more planar surface than the first tendency of planarity (shown in block 3130). The central tendency of planarity may be measured in terms of the central tendency of roughness.

[0279] Optionally, the second layer has a thickness having a fourth central tendency of thickness of the same type as the second central tendency of thickness, wherein during use of the material dispenser, a closest distance between the target surface and the material dispenser is larger than (a) the second central tendency of thickness of the first layer and/or (b) the fourth central tendency of thickness of the second layer (shown in block 3140).

[0280] Optionally, the agitator is separated from the material dispenser (shown in block 3150). The agitator may comprise a panel (e.g., Fig. 22, panel 2210) that is separated (e.g., ultrasonically isolated) from the material dispenser (e g., reservoir 2202 of a material dispenser 2200). The agitator may be located at least partially within a volume of powder material (e.g., powder material 2204) retained within a reservoir (e.g., reservoir 2202) of the material material dispenser and separated from the walls of the reservoir.

[0281] Optionally, the agitator is operatively coupled to a panel that is operatively coupled to, or that is part of, the material dispenser, the panel being arranged with respect to the exit port of the material dispenser, the method further comprises (c) restricting, by the panel and in the first operating state, a flow of the powder material through the exit port of the material dispenser and (d) allowing, by the panel and in the second operating state, the flow of the powder material from the exit port of the material dispenser towards the target surface (shown in block 3160). The agitator may be operatively coupled to a panel of the material dispenser, e.g., Fig. 19, agitator 1904 in mechanical contact with a panel 1940 of a material dispenser 1950.

[0282] Optionally, a transducer of the agitator is disposed outside of a processing chamber enclosing the first layer (shown in block 3170). For example, in Fig. 24, a transducer 2406 may be coupled (e.g., via couplers 2408) to a reservoir 2410. The transducer may be isolated from an inner atmosphere 1026 of a processing chamber.

[0283] Optionally, the method further comprises controlling a dew point of an interior atmosphere of the processing chamber to be (III) above a level of humidity at or below which the powder material agglomerates, and (IV) below a level in which the powder material absorbs water (e) such that the powder material becomes reactive under conditions of a three- dimensional printing process utilizing the powder material and/or (f) such that the absorbed water on the powder material is sufficient to cause a measurable defect in a three-dimensional object printed from the powder material (shown in block 3180). In some embodiments, a 3D printing system comprises a processing chamber, build module, gas flow system, recycling system (e.g., for gas and/or pre-transformed material), optical system, layer dispensing mechanism, garage, control system, and/or structural supports. In some embodiments, an enclosure comprises a processing chamber. The processing chamber may be in fluidic contact with a gas flow mechanism. The gas flow mechanism can comprise structures that at least partially dictate the flowing of gas across (e.g., through, within, or the like) the (e.g., entire) processing chamber and/or a portion of the processing chamber.

[0284] Any of the various options of the process shown in Fig. 31 can be omitted. The optional operations of the method can be performed in any order.

[0285] Fig. 32 shows an example of a 3D printing system 3200 disposed in relation to gravitational vector 3290 directed towards gravitational center G. The 3D printing system comprises processing chamber 3201 coupled to an ancillary chamber (e.g., garage) 3202 configured to accommodate a layer dispensing mechanism (e.g., recoater), e.g., in its resting (e.g., idle) position. The processing chamber is coupled to a build module 3203 that extends 3204 under a plane (e.g, floor) at which user 3205 stands on (e.g., can extend under-grounds). The processing chamber may comprise a door (not shown) facing user 3205. 3D printing system 3200 comprises enclosure 3206 that can comprise an energy beam alignment system (e.g., an optical system) and/or an energy beam directing system (e.g., scanner) - not shown. A layer dispensing mechanism (not shown) may be coupled to a framing 3207 as part of a movement system that facilitate movement of the layer dispensing mechanism along the material bed and garage (e.g., in a reversible back-and-forth movement). The movement system comprises a translation inducer system (e.g., comprising a belt or a chain 3208). 3D printing system 3200 comprises a filter unit 3209, heat exchangers 3210a and 3210b, pre-transformed material reservoir 3211 , and gas flow mechanism (e.g., comprising gas inlets and gas inlet portions) disposed in enclosure 3213. The filtering system may filter gas and/or pre-transformed (e.g., powder) material. The filtering system may be configured to filter debris (e.g., comprising byproduct(s) of the 3D printing).

[0286] Fig. 33 shows in example 3300 a front side example of a portion of a 3D printing system comprising a material reservoir 3301 configured to feed pre-transformed material to a layer dispensing mechanism, an enclosure 3309 configured to enclosure, e.g., scanner(s) and/or director(s) (e.g., optical system) of at least one energy beam (e.g., laser beam) configured to transform the pre-transformed material into a transformed material to print one or more 3D object in a printing cycle. Example 3300 of Fig. 33 shows a build module 3302 having a door with three circular viewing windows. The windows may be any window disclosed herein. The viewing window may be a single or a double pane window. The window may be an insulated glass unit (IGU), the window may be configured to withstand positive pressure within the processing chamber, e.g., during printing. The positive pressure is above ambient pressure external to the build module, e.g., the ambient pressure may be about one atmosphere. Example 3300 show a material reservoir 3304 configured to accumulate recycled remainder starting material (e.g., pre-transformed material) from the layer dispensing process to form a material bed and/or a remainder of the material bed that did not form one or more 3D objects during a printing cycle, post 3305 as part of an elevator mechanism of build module 3308; two material reservoirs 3307 for accumulating a remainder of the material bed that did not form the 3D object, and actuator 3303 configured to translate the layer dispensing mechanism to dispense a layer of pre-transformed material as part of a material bed. Supports 3306 are planarly stationed in a first horizontal plane, which supports 3306 and associated framing support one section of the 3D printing system portion 3300, and framing 3310 is disposed on a second horizontal plane higher than the first horizontal plane. Fig. 33 shows in 3350 an example side view example of a portion of the 3D printing system shown in example 3300, which side view comprises a material reservoir 3351 configured to feed pre-transformed material to a layer dispensing mechanism, an enclosure 3359 enclosing, e.g., scanners and/or directors (e.g., optical system) of at least one energy beam (e.g., laser beam) configured to transform the pretransformed material into a transformed material to print one or more 3D object in a printing cycle. Example 3350 of Fig. 33 shows an example of a build module 3352 having a door comprising handle 3369 (as part of a handle assembly). Example 3300 show a material reservoir 3354 configured to accumulate recycled remainder from the layer dispensing process to form a material bed and/or a remainder of the material bed that did not form one or more 3D objects during a printing cycle, a portion of the material conveyance system 3368 configured to convey the material to reservoir 3354. The material conveyed to reservoir 3354 may be separated (e.g., sieved) before reaching reservoir 3354. The example shown in 3350 shows post 3355 as part of an elevator mechanism of build module 3358; two material reservoirs 3357 for accumulating a remainder of the material bed that did not form the 3D object, and actuator 3353 configured to translate the layer dispensing mechanism to dispense a layer of pretransformed material as part of a material bed, e.g., along railing 3367 in processing chamber and into garage 3366 in a reversible (e.g., back and forth) movement. Supports 3356 are planarly stationed in a first horizontal plane, which supports 3306 and associated framing support one section of the 3D printing system portion 3350, and framing 3360 is disposed on a second horizontal plane higher than the first horizontal plane. In the example shown in Fig. 33, the 3D printing system components may be aligned with respect to gravitational vector 3390 pointing towards gravitational center G. [0287] In some embodiments, the systems, apparatuses, and/or components thereof comprise one or more controllers. The one or more controllers can comprise one or more central processing unit (CPU), input/output (I/O) and/or communications module. The CPU can comprise electronic circuitry that carries out instructions of a computer program by performing basic arithmetic, logical, control and I/O operations specified by the instructions. The controller can comprise a suitable software (e.g., operating system). The control system may optionally include a feedback control scheme (e.g., loop) and/or feed-forward control scheme. The controllers may be shared between one or more systems or apparatuses. Each apparatus or system may have its own controller. Two or more systems and/or its components may share a controller. Two or more apparatuses and/or its components may share a controller. The controller may monitor and/or direct (e.g., physical) alteration of the operating conditions of the apparatuses, software, and/or methods described herein. The controller may be a manual or a non-manual controller. The controller may be an automatic controller. The controller may operate upon request. The controller may be a programmable controller. The controller may be programed. The controller may comprise a processing unit (e.g., CPU or GPU). The controller may receive an input (e.g., from a sensor). The controller may deliver an output. The controller may comprise multiple controllers. The controller may receive multiple inputs. The controller may generate multiple outputs. The controller may be a single input single output controller (SISO) or a multiple input multiple output controller (MIMO). The controller may interpret the input signal received. The controller may acquire data from the one or more sensors. Acquire may comprise receive or extract. The data may comprise measurement, estimation, determination, generation, or any combination thereof. The controller may comprise feedback control. The controller may comprise feed-forward control. The control may comprise on-off control, proportional control, proportional-integral (PI) control, or proportional-integral-derivative (PID) control. The control may comprise open loop control, or closed loop control. The controller may comprise closed loop control. The controller may comprise open loop control. The controller may comprise a user interface. The user interface may comprise a keyboard, keypad, mouse, touch screen, microphone, speech recognition package, camera, imaging system, or any combination thereof. The outputs may include a display (e.g., screen), speaker, or printer. Examples of 3D printing systems and their components, 3D printing processes, 3D objects, control systems, and software can be found in US Patent Application serial number 18/207,206 filed on June 8, 2023; in International Patent Application serial number PCT/US17/18191 filed February 16, 2017; and International Patent Application serial number PCT/US16/59781 filed on October 31 , 2016; each of which is incorporated herein by reference in its entirety.

[0288] At times, the one or more controllers are operable to control operations of a fluidizing element, e.g., a transducer coupled to an agitator, of the layer dispensing mechanism. The controllers may provide instructions (e.g., control signals) to the fluidizing element via wireless control and/or wired control. The controllers may provide control signals for inducing vibrational motion in the fluidizing element, e.g., in the waveguide. For example, a transducer may be located outside (e.g., in an atmosphere external to the enclosure) the processing chamber and is coupled to an agitator that is part of the layer dispensing mechanism (e.g., located within the atmosphere of the enclosure). At times, the one or more controllers are operable to control operations comprising actuation of one or more planes, e.g., shutters, flaps, irises, or another mechanical gate. At times, the one or more controllers are operable to control an orientation of a plane, e.g., adjust an angle of a plane that is a part of the layer dispensing mechanism.

[0289] At times, the one or more controllers may control dispense characteristics for the dispense of powder from the layer dispensing mechanism, e.g., volume of dispensed layer, thickness of dispensed layer, planarity of dispensed layer, speed of dispense, or the like. The one or more controllers may utilize feedback loops, for example, (A) a feed forward control, (B) feedback control, (C) closed loop control, or (D) a combination thereof, to adjust dispense characteristics of the layer dispensing mechanism. Adjusting of dispense characteristics may occur in real-time. The one or more controllers may adjust dispense characteristics, in part, based at least in part on (A) powder composition, (B) flowability changes in the powder, (C) atmospheric conditions (e.g., humidity levels), (D) volume of powder in a reservoir of the layer dispensing mechanism, or (E) any combination of (A)-(D). In some instances, historical values or a look up table can be utilized to determine dispense characteristics for the layer dispensing mechanism for a given pre-transformed material and/or operating conditions. In some instances, a machine learned model can be trained to adjust dispense characteristics in response to changes in operating conditions and/or for a given pre-transformed material. Multiple of tuning schemes can be generated for the one or more controllers, each tuning scheme selectable for a set of operating conditions and/or powder characteristics. For example, tuning scheme may utilize (i) a look-up table (LUT), (ii) historical data, (iii) experiments, (iv) physics simulation, (v) artificial intelligence, (vi) data analysis, and/or (vii) the like. The artificial intelligence may comprise training a plant model (a machine-learned model). The artificial intelligence may comprise data analysis. The training model may be trained utilizing (i) a look-up table (LUT), (ii) historical data, (iii) experiments, (iv) synthesized results from physics simulation, or (v) the like. In some embodiments, control scheme(s) can use a single plant model and project changes due to the temperature based at least in part on previously identified models. The control scheme(s) may be inscribed as program instructions (e.g., software).

[0290] In some embodiments, the control scheme used the controller(s) disclosed herein involve data analysis. The data analysis techniques involve one or more regression analys(es) and/or calculation(s). The regression analysis and/or calculation may comprise linear regression, least squares fit, Gaussian process regression, kernel regression, nonparametric multiplicative regression (NPMR), regression trees, local regression, semiparametric regression, isotonic regression, multivariate adaptive regression splines (MARS), logistic regression, robust regression, polynomial regression, stepwise regression, ridge regression, lasso regression, elasticnet regression, principal component analysis (PCA), singular value decomposition (SVD)), probability measure techniques (e.g., fuzzy measure theory, Borel measure, Harr measure, riskneutral measure, Lebesgue measure), predictive modeling techniques (e.g., group method of data handling (GMDH), Naive Bayes classifiers, -nearest neighbors algorithm (k-NN), support vector machines (SVMs), neural networks, support vector machines, classification and regression trees (CART), random forest, gradient boosting, generalized linear model (GLM)), or any other suitable probability and/or statistical analys(es). The learning scheme may comprise neural networks. The leaning scheme may comprise machine learning. The learning scheme may comprise pattern recognition. The learning scheme may comprise artificial intelligence, data miming, computational statistics, mathematical optimization, predictive analytics, discrete calculus, or differential geometry. The learning schemes may comprise supervised learning, reinforcement learning, unsupervised learning, semi-supervised learning. The learning scheme may comprise bias-variance decomposition. The learning scheme may comprise decision tree learning, associated rule learning, artificial neural networks, deep learning, inductive logic programming, support vector machines, clustering, Bayesian networks, reinforcement learning, representation learning, similarity and metric learning, sparse dictionary learning, or genetic algorithms (e.g., evolutional algorithm). The non-transitory computer media may comprise any of the computational schemes (e.g., algorithms) disclosed herein. The controller and/or processor may comprise the non-transitory computer media. The software may comprise any of the computational schemes disclosed herein. The controller and/or processor may comprise the software. The learning scheme may comprise random forest scheme.

[0291] In some embodiments, the control system utilizes a physics simulation in, e.g., in a computer model (e.g., comprising a prediction model, statistical model, a thermal model, or a thermo-mechanical model). The computer model may provide feedforward information to the control system. The computer model may provide the feed forward control scheme. There may be more than one computer models (e.g. at least 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 different computer models). The controller may (e.g., dynamically) switch between the computer models to predict and/or estimate the behavior of the optical elements. Dynamic includes changing computer models (e.g., in real time) based at least in part on a sensor input or based at least in part on a controller decision that may in turn be based at least in part on monitored target temperature. The dynamic switch may be performed in real-time, e.g., during operation of the optical system and/or during printing 3D object(s). The controller may be configured (e.g., reconfigured) to include additional one or more computer models and/or readjust the existing one or more computer models. A prediction may be done offline (e.g., predetermined) and/or in real-time. Examples of the calibration, control systems, controllers and operation thereof, 3D printing systems and processes, apparatus, methods, and computer programs, are disclosed in International Patent Application serial number PCT/US19/14635, filed January 22, 2019, that is incorporated herein by reference in its entirety. [0292] In some instances, the processing unit includes one or more cores. The computer system may comprise a single core processor, multi core processor, or a plurality of processors for parallel processing. The processing unit may comprise one or more central processing unit (CPU) and/or a graphic processing unit (GPU). The multiple cores may be disposed in a physical unit (e.g., Central Processing Unit, or Graphic Processing Unit). The processing unit may include one or more processing units. The physical unit may be a single physical unit. The physical unit may be a die. The physical unit may comprise cache coherency circuitry. The multiple cores may be disposed in close proximity. The physical unit may comprise an integrated circuit chip. The integrated circuit chip may comprise one or more transistors. The close proximity may allow substantial preservation of communication signals that travel between the cores. The close proximity may diminish communication signal degradation. A core as understood herein is a computing component having independent central processing capabilities. The computing system may comprise a multiplicity of cores, which may be disposed on a single computing component. The multiplicity of cores may include two or more independent central processing units. The independent central processing units may constitute a unit that read and execute program instructions. The independent central processing units may constitute parallel processing units. The parallel processing units may be cores and/or digital signal processing slices (DSP slices). The multiplicity of cores can be parallel cores. The multiplicity of DSP slices can be parallel DSP slices. The multiplicity of cores and/or DSP slices can function in parallel. In some processors (e.g., FPGA), the cores may be equivalent to multiple digital signal processor (DSP) slices (e.g., slices). The plurality of DSP slices may be equal to any of plurality core values mentioned herein. The processor may comprise low latency in data transfer (e.g., from one core to another). Latency may refer to the time delay between the cause and the effect of a physical change in the processor (e.g., a signal). Latency may refer to the time elapsed from the source (e.g., first core) sending a packet to the destination (e.g., second core) receiving it (also referred as two-point latency). One-point latency may refer to the time elapsed from the source (e.g., first core) sending a packet (e.g., signal) to the destination (e.g., second core) receiving it, and the designation sending a packet back to the source (e.g., the packet making a round trip). The latency may be sufficiently low to allow a high number of floating point operations per second (FLOPS).

[0293] In some instances, the computer system includes hyper-threading technology. The computer system may include a chip processor with integrated transform, lighting, triangle setup, triangle clipping, rendering engine, or any combination thereof. The rendering engine may be capable of processing at least about 10 million polygons per second. The rendering engines may be capable of processing at least about 10 million calculations per second. As an example, the GPU may include a GPU by Nvidia, ATI Technologies, S3 Graphics, Advanced Micro Devices (AMD), or Matrox. The processing unit may be able to process schemes (e.g., algorithms) comprising a matrix or a vector. The core may comprise a complex instruction set computing core (CISC), or reduced instruction set computing (RISC).

[0294] In some instances, the computer system includes an electronic chip that is reprogrammable (e.g., field programmable gate array (FPGA)). For example, the FPGA may comprise Tabula, Altera, or Xilinx FPGA. The electronic chips may comprise one or more programmable logic blocks (e.g., an array). The logic blocks may compute combinational functions, logic gates, or any combination thereof. The computer system may include custom hardware. The custom hardware may comprise a computational scheme.

[0295] In some instances, the computer system includes configurable computing, partially reconfigurable computing, reconfigurable computing, or any combination thereof. The computer system may include a FPGA. The computer system may include an integrated circuit that performs the computational scheme. For example, the reconfigurable computing system may comprise FPGA, CPU, GPU, or multi-core microprocessors. The reconfigurable computing system may comprise a High-Performance Reconfigurable Computing architecture (HPRC). The partially reconfigurable computing may include module-based partial reconfiguration, or difference-based partial reconfiguration. The FPGA may comprise configurable FPGA logic, and/or fixed-function hardware comprising multipliers, memories, microprocessor cores, first in- first out (FIFO) and/or error correcting code (ECC) logic, digital signal processing (DSP) blocks, peripheral Component interconnect express (PCI Express) controllers, ethernet media access control (MAC) blocks, or high-speed serial transceivers. DSP blocks can be DSP slices.

[0296] In some examples, the computing system includes an integrated circuit. The computing system may include an integrated circuit that performs the computational scheme such as an algorithm (e.g., control algorithm). In some instances, the controller uses calculations, real time measurements, or any combination thereof to regulate the energy beam(s).

[0297] Aspects of the systems, apparatuses, and/or methods provided herein, such as the computer system, can be embodied in programming (e.g., using a software). Various aspects of the technology may be thought of as “product,” “object,” or “articles of manufacture” typically in the form of machine (or processor) executable code and/or associated data that is carried on or embodied in a type of machine-readable medium. Machine-executable code can be stored on an electronic storage unit, such memory (e.g., read-only memory, random-access memory, flash memory) or a hard disk. The storage may comprise non-volatile storage media. “Storage” type media can include any or all of the tangible memory of the computers, processors or the like, or associated modules thereof, such as various semiconductor memories, tape drives, disk drives, external drives, and the like, which may provide non-transitory storage at any time for the software programming.

[0298] In some examples, the computer system comprises a memory. The memory may comprise a random-access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), synchronous dynamic random access memory (SDRAM), ferroelectric random access memory (FRAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), a flash memory, or any combination thereof. The flash memory may comprise a negative-AND (NAND) or NOR logic gates. A NAND gate (negative-AND) may be a logic gate which produces an output which is false only if all its inputs are true. The output of the NAND gate may be complemented to that of the AND gate. The storage may include a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optic disk, a solid-state disk, etc.), a compact disc (CD), a digital versatile disc (DVD), a floppy disk, a cartridge, a magnetic tape, and/or another type of computer-readable medium, along with a corresponding drive.

[0299] In some instances, all or portions of the software are at times communicated through the Internet and/or other telecommunication networks. Such communications, for example, may enable loading of the software from one computer or processor into another, for example, from a management server or host computer into the computer platform of an application server. Thus, another type of media that may bear the software elements includes optical, electrical, and electromagnetic waves, such as used across physical interfaces between local devices, through wired and optical landline networks and over various air-links. The physical elements that carry such waves, such as wired or wireless links, optical links, or the like, also may be considered as media bearing the software. As used herein, unless restricted to non-transitory, tangible “storage” media, terms such as computer or machine “readable medium” refer to any medium or media that participate(s) in providing instructions to a processor for execution.

[0300] In some embodiments, the computer system utilizes a machine readable medium/media to execute, or direct execution of, operation(s). The program instructions can be inscribed in a machine executable code. A machine-readable medium/media, such as computerexecutable code, may take many forms, including but not limited to, a tangible storage medium, a carrier wave medium, or physical transmission medium. Non-volatile storage media include, for example, optical or magnetic disks, such as any of the storage devices in any computer(s) or the like, such as may be used to implement the databases. Volatile storage media can include dynamic memory, such as main memory of such a computer platform. Tangible transmission media can include coaxial cables, wire (e.g., copper wire), and/or fiber optics, including the wires that comprise a bus within a computer system. Carrier-wave transmission media may take the form of electric or electromagnetic signals, or acoustic or light waves such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media therefore include for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any other optical medium, punch cards paper tape, any other physical storage medium with patterns of holes, a RAM, a ROM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting such a carrier wave, any other medium from which a computer may read programming code and/or data, or any combination thereof. The memory and/or storage may comprise a storing device external to and/or removable from device, such as a Universal Serial Bus (USB) memory stick, or/and a hard disk. Many of these forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution.

[0301] In some instances, the computer system comprises an electronic display. The computer system can include or be in communication with an electronic display that comprises a user interface (Ul) for providing, for example, a model design or graphical representation of a 3D object to be printed. Examples of Ul’s include, without limitation, a graphical user interface (GUI) and web-based user interface. The computer system can monitor and/or control various aspects of the 3D printing system. The control may be manual and/or programmed. The control may rely on feedback mechanisms (e.g., from the one or more sensors). The control may rely on historical data. The feedback mechanism may be pre-programmed. The feedback mechanisms may rely on input from sensors (described herein) that are connected to the control unit (i.e., control system or control mechanism e.g., computer) and/or processing unit. The computer system may store historical data concerning various aspects of the operation of the 3D printing system. The historical data may be retrieved at predetermined times and/or at a whim. The historical data may be accessed by an operator and/or by a user. The historical, sensor, and/or operative data may be provided in an output unit such as a display unit. The output unit (e.g., monitor) may output various parameters of the 3D printing system (as described herein) in real time or in a delayed time. The output unit may output the current 3D printed object, the ordered 3D printed object, or both. The output unit may output the printing progress of the 3D printed object. The output unit may output at least one of the total time, time remaining, and time expanded on printing the 3D object. The output unit may output (e.g., display, voice, and/or print) the status of sensors, their reading, and/or time for their calibration or maintenance. The output unit may output the type of material(s) used and various characteristics of the material(s) such as temperature and flowability of the pre-transformed material. The output unit may output the amount of oxygen, water, and pressure in the printing chamber (i.e., the chamber where the 3D object is being printed). The computer may generate a report comprising various parameters of the 3D printing system, method, and or objects at predetermined time(s), on a request (e.g., from an operator), and/or at a whim. The output unit may comprise a screen, printer, or speaker. The control system may provide a report. The report may comprise any items recited as optionally output by the output unit.

[0302] In some instances, the system and/or apparatus described herein (e.g., controller) and/or any of their components comprise an output and/or an input device. The input device may comprise a keyboard, touch pad, or microphone. The output device may be a sensory output device. The output device may include a visual, tactile, or audio device. The audio device may include a loudspeaker. The visual output device may include a screen and/or a printed hard copy (e.g., paper). The output device may include a printer. The input device may include a camera, a microphone, a keyboard, or a touch screen.

[0303] In some instances, the computer system includes a user interface. The computer system can include, or be in communication with, an electronic display unit that comprises a user interface (Ul) for providing, for example, a model design or graphical representation of an object to be printed. Examples of Ul’s include a graphical user interface (GUI) and web-based user interface. The historical and/or operative data may be displayed on a display unit. The computer system may store historical data concerning various aspects of the operation of the cleaning system. The historical data may be retrieved at predetermined times and/or at a whim. The historical data may be accessed by an operator and/or by a user. The display unit (e.g., monitor) may display various parameters of the printing system (as described herein) in real time or in a delayed time. The display unit may display the requested printed 3D object (e.g., according to a model), the printed 3D object, real time display of the 3D object as it is being printed, or any combination thereof. The display unit may display the cleaning progress of the object, or various aspects thereof. The display unit may display at least one of the total time, time remaining, and time expanded on the cleaned object during the cleaning process. The display unit may display the status of sensors, their reading, and/or time for their calibration or maintenance. The display unit may display the type or types of material used and various characteristics of the material or materials such as temperature and flowability of the pretransformed material. The display unit may display the amount of a certain gas in the chamber. The gas may comprise an oxidizing gas (e.g., oxygen), hydrogen, water vapor, or any of the gasses mentioned herein. The gas may comprise a reactive agent. The display unit may display the pressure in the chamber. The computer may generate a report comprising various parameters of the methods, objects, apparatuses, or systems described herein. The report may be generated at predetermined time(s), on a request (e.g., from an operator) or at a whim.

[0304] Methods, apparatuses, and/or systems of the present disclosure can be implemented by way of one or more computational schemes. A computational scheme can be implemented by way of software upon execution by one or more computer processors. For example, the processor can be programmed to calculate the path of the energy beam and/or the power per unit area emitted by the energy source (e.g., that should be provided to the material bed in order to achieve the requested result). Examples of 3D printing systems and their components, 3D printing processes, 3D objects, control systems (and control schemes), and software can be found in International Patent Application Serial No. PCT/US17/18191 , filed February 16, 2017, that is incorporated herein by reference in their entirety.

[0305] In some embodiments, the 3D printer comprises and/or communicates with a plurality of processors. The processors may form a network architecture. The 3D printer may comprise at least one processor (referred herein as the “3D printer processor”). The 3D printer may comprise a plurality of processors. At least two of the plurality of the 3D printer processors may interact with each other. At times, at least two of the plurality of the 3D printer processors may not interact with each other.

[0306] In some embodiments, a 3D printer processor interacts with at least one processor that acts as a 3D printer interface (also referred to herein as “machine interface processor”). The processor (e.g., machine interface processor) may be stationary or mobile. The processor may be a remote computer systems. The machine interface one or more processors may be connected to at least one 3D printer processor. The connection may be through a wire (e.g., cable) and/or be wireless (e.g., via Bluetooth technology). The machine interface may be hardwired to the 3D printer. The machine interface may directly connect to the 3D printer (e.g., to the 3D printer processor). The machine interface may indirectly connect to the 3D printer (e.g., through a server, or through wireless communication). The cable may comprise coaxial cable, shielded twisted cable pair, unshielded twisted cable pair, structured cable (e.g., used in structured cabling), or fiber-optic cable.

[0307] In some embodiments, the machine interface processor directs 3D print job production, 3D printer management, 3D printer monitoring, or any combination thereof. The machine interface processor may not be able to influence (e.g., direct, or be involved in) pre-print or 3D printing process development. The machine management may comprise controlling the 3D printer controller (e.g., directly or indirectly). The printer controller may direct start (e.g., initiation) of a 3D printing process, stopping a 3D printing process, maintenance of the 3D printer, clearing alarms (e.g., concerning safety features of the 3D printer).

[0308] In some embodiments, the machine interface processor allows monitoring of the 3D printing process (e.g., accessible remotely or locally). The machine interface processor may allow viewing a log of the 3D printing and status of the 3D printer at a certain time (e.g., 3D printer snapshot). The machine interface processor may allow to monitor one or more 3D printing parameters. The one or more printing parameters monitored by the machine interface processor can comprise 3D printer status (e.g., 3D printer is idle, preparing to 3D print, 3D printing, maintenance, fault, or offline), active 3D printing (e.g., including a build module number), status and/or position of build module(s), status of build module and processing chamber engagement, type and status of pre-transformed material used in the 3D printing (e.g., amount of pre-transformed material remaining in the reservoir), status of a filter, atmosphere status (e.g., pressure, gas level(s)), ventilator status, layer dispensing mechanism status (e.g., position, speed, rate of deposition, level of exposed layer of the material bed), status of the optical system (e.g., optical window, mirror), status of scanner, alarm (, boot log, status change, safety events, motion control commands (e.g., of the energy beam, or of the layer dispensing mechanism), or printed 3D object status (e.g., what layer number is being printed), [0309] In some embodiments, the machine interface processor allows controlling (e.g., monitoring) the 3D print job management. The 3D print job management may comprise status of each build enclosure, e.g., atmosphere condition, power levels of the energy beam, type of pre- transformed material loaded, 3D printing operation diagnostics, status of a filter, or the like. The machine interface processor (e.g., output device thereof) may allow viewing and/or editing any of the job management and/or one or more printing parameters. The machine interface processor may show the permission level given to the user (e.g., view, or edit). The machine interface processor may allow prioritize 3D objects to be printed, pause 3D objects during 3D printing, delete 3D objects to be printed, select a certain 3D printer for a particular 3D printing job, insert and/or edit considerations for restarting a 3D printing job that was removed from 3D printer. The machine interface processor may allow initiating, pausing, and/or stopping a 3D printing job. The machine interface processor may output message notification (e.g., alarm), log (e.g., other than Excursion log or other default log), or any combination thereof.

[0310] In some embodiments, the 3D printer interacts with at least one server (e.g., print server). The 3D print server may be separate or interrelated in the 3D printer. One or more users may interact with the one or more 3D printing processors through one or more user processors (e.g., respectively). The interaction may be in parallel and/or sequentially. The users may be clients. The users may belong to entities that request a 3D object to be printed, or entities who prepare the 3D object printing instructions. The one or more users may interact with the 3D printer (e.g., through the one or more processors of the 3D printer) directly and/or indirectly. Indirect interaction may be through the server. One or more users may be able to monitor one or more aspects of the 3D printing process. One or more users can monitor aspects of the 3D printing process through at least one connection (e.g., network connection). For example, one or more users can monitor aspects of the printing process through direct or indirect connection. Direct connection may be using a local area network (LAN), and/or a wide area network (WAN). The network may interconnect computers within a limited area (e.g., a building, campus, neighborhood). The limited area network may comprise Ethernet or Wi-Fi. The network may have its network equipment and interconnects locally managed. The network may cover a larger geographic distance than the limited area. The network may use telecommunication circuits and/or internet links. The network may comprise Internet Area Network (IAN), and/or the public switched telephone network (PSTN). The communication may comprise web communication. The aspect of the 3D printing process may comprise a 3D printing parameter, machine status, or sensor status. The 3D printing parameter may comprise hatch strategy, energy beam power, energy beam speed, energy beam focus, thickness of a layer (e.g., of hardened material or of pre-transformed material).

[0311] In some embodiments, a user develops at least one 3D printing instruction and directs the 3D printer (e.g., through communication with the 3D printer processor) to print in a requested manner according to the developed at least one 3D printing instruction. A user may or may not be able to control (e.g., locally or remotely) the 3D printer controller, e.g., depending on permission preferences. For example, a client may not be able to control the 3D printing controller (e.g., maintenance of the 3D printer). [0312] In some embodiments, the user (e.g., other than a client) processor may use real-time and/or historical 3D printing data of one or more 3D printers. The 3D printing data may comprise metrology data. The user processor may comprise quality control. The quality control may use a statistical method (e.g., statistical process control (SPC)). The user processor may log excursion log, report when a signal deviates from the nominal level, or any combination thereof. The user processor may generate a configurable response. The configurable response may comprise a print/pause/stop command (e.g., automatically) to the 3D printer (e.g., to the 3D printing processor). The configurable response may be based at least in part on a user defined parameter, threshold, or any combination thereof. The configurable response may result in a user defined action. The user processor may control the 3D printing process and ensure that it operates at its full potential. For example, at its full potential, the 3D printing process may make a maximum number of 3D object with a minimum of waste and/or 3D printer down time. The SPC may comprise a control chart, design of experiments, and/or focus on continuous improvement.

[0313] In some embodiments, the exit opening of the material dispenser is separated from a planar surface of the panel by a gap, the panel being configured to cause material disposed on its planar surface to become agitated, e.g., to vibrate. A FLS (e.g., height) of the gap may be small, e.g., relative to the FLS (e.g., width) of the exit opening. A FLS may be sensitive, e.g., to physical disturbance. A bumper may be affixed to the material dispenser to protect the gap from (e.g., direct) physical disturbance. For example, the bumper may protect the gap from (e.g., direct) movement of the panel, e.g., of the planar portion of the panel acting as a waveguide such as 3464a in Fig. 34. In some embodiments, the bumper is absent.

[0314] In some embodiment, the panel comprises a first portion configured to guide agitation with minimal dampening, and a second portion configured to dampen the agitation. The second portion may be configured as an agitation black hole. The agitation may comprise vibration such as mechanical vibration. The agitation may comprise vibration such as acoustic vibration. The acoustic vibration may comprise ultrasonic vibration. The agitation black hole may comprise a vibrational black hole. The first portion of the panel may have a least one FLS that is constant along a direction of the first portion. In an example, the first portion of the panel has (e.g., substantially) the same horizontal cross section along its vertical length, and (e.g., substantially) the same vertical cross section along its horizontal length. The second portion of the panel may comprise an inhomogeneity in the panel, e.g., a structural inhomogeneity and/or a material (e.g., chemical) inhomogeneity. In an example, the second portion of the panel tapers along the length of the second portion to a minimal thickness (e.g., to zero thickness). The tapering may be symmetric or asymmetric with respect to a thickness of the panel. For example, a cross section in the tapering portion is a right triangle, or an isosceles triangle. In some embodiments, a third portion connects the first portion with the second portion. The third portion may comprise a curvature, e.g., the third portion may be bent. The panel (including its portions) may be formed from one piece of material. The panel may be formed at least in part by using a machining technique comprising milling or electrical distortion. The milling may comprise computer- numerical control (CNC) machine milling. The machining technique may be configured to minimally induce stress in the material. The machining technique may be configured to minimally alter the speed of agitation propagating in the material, e.g., minimally alter the speed of vibrations propagating in the material, e.g., minimally alter the speed of sound propagating in the material. The first (e.g., planar) portion of the panel may be configured to minimally attenuate (e.g., dampen) the agitation traveling therethrough. The agitation may comprise vibrations such as acoustic vibrations. The third (e.g., bent) portion of the panel may be configured to minimally attenuate (e.g., dampen) the agitation traveling therethrough. The second (e.g., tapered) portion of the panel may be configured to maximally attenuate (e.g., dissipate and/or dampen) the agitation traveling therethrough as the agitation propagates into the second portion and away from the first portion. The second portion may be disposed at an angle with respect to the first portion. The angle may be at least about 0.5°, 1 °, 5°, 10°, 20°, 30°, 40°, 45°, 50°, 60°, 70°, 80°, 90°, 100°, or 110°. The angle may be configured to minimize an extent of the panel beyond a FLS direction of the material bed normal (e.g., perpendicular) to which the material dispenser propagates during operation. The angle may be configured to minimize an extent of the panel in a FLS direction of the processing chamber, to allow the material dispenser to propagate laterally in a direction normal (e.g., perpendicular) to that FLS direction during operation.

[0315] In some embodiments, the material dispenser comprises, or is operatively coupled with, an agitation black hole. For example, with a vibrational acoustic black hole (ABH). The ABH may comprise the second portion of the panel that is inhomogeneous. The inhomogeneity may increase the more distant the second portion is from the first portion. For example, the second portion becomes narrower and narrower the more it is distant from the first portion (that is a waveguide). For example, the second portion may contact (e.g., become engulfed) with a larger volume of damping material (e.g., vibrational absorber). The ABH structure may comprise (a) an inhomogeneous (e.g., tapering) portion of the panel and (b) an agitation (e.g., vibrational) absorber. The absorber may be a viscoelastic material. The absorber may be configured to snuggly contact the exposed surface of the inhomogeneous (second) portion of the panel. The absorber may be configured to conformally press onto the inhomogeneous (second) portion of the panel. The absorber may be configured to compress onto the inhomogeneous portion of the panel. The ABH structure may comprise an insert (e.g., a wedge) that causes the absorber to press onto the tapering portion of the panel, e.g., to increase physical contact between the absorber and the inhomogeneous (e.g., tapering) portion of the panel. The insert may be configured to cause the absorber to press in a conformal compression onto the second portion of the panel. For example, the insert may be configured to exert a conformal compression upon the absorber pressing in a conformal compression onto the second portion of the panel. The absorber may comprise one or more sheets between which the second portion of the panel is disposed. The absorber may engulf the second portion of the panel. The absorber may be generated using injection molding, or polymerization. The absorber may comprise silicone, rubber, or polyurethane. The absorber may be compressible. The housing may be configured to allow the absorber to be held in place (e.g., and compressed upon the second panel portion) during operation. During the operation comprises during agitation of the panel, e.g., during propagation of the vibrations in the panel. The absorber may be configured to dampen and/or dissipate the agitations, e.g., configured to dampen and/or dissipate the agitative energy. The panel may comprise a material having high sound conductivity, e.g., which facilitates transfer of agitation (e.g., vibration) therethrough with minimal energetic loss. In an example, the panel comprises an elemental metal or a metal alloy. In an example, the panel comprises a material having high sound conductivity comprising aluminum, copper, gold, silver, titanium, or steel. In an example, the panel is devoid of a material that has low sound conductivity. The low sound conducting material may include cast iron and/or forged iron. In an example, the panel is devoid of a material having a greater efficiency of converting (e.g., acoustic) vibrations to heat than that the high sound conducting materials. In an example, the panel is of a material having a lower (e.g., lesser) conversion efficiency of (e.g., acoustic) vibrations to heat than the low sounds conducting material. The agitation black hole may be configured to slow down, dampen, and/or dissipate the agitation energy as the agitation propagates away from the agitating portion of the panel (e.g., first portion of the panel) and into the black hole related portion of the panel (e.g., second portion of the panel). The agitation black hole (e.g., second) portion may be configured to slow down the agitation as it is propagating in the material. The agitation black hole may be configured to absorb the high amplitude agitations, e.g., vibrations. The agitation black hole may be configured to attenuate the agitation to (e.g., substantially) zero at the end of the panel in which the black hole portion of the panel is disposed (e.g., second portion of the panel).

[0316] In some embodiments, the first portion of the panel is suspended below the exit opening of the material dispenser. In an example, the first portion of the panel is configured to receive the exiting material thereon. The first portion of the panel may be held at a distance (e.g., gap) from the exit opening at least in part by being coupled to the vibration actuator (e.g., vibration inducer) on one end, and by clamping a second potion of the panel in a housing. The housing may be (a) affixed with a body of the material dispenser and/or (b) be part of the body of the material dispenser. For example, a first portion of the housing may be reversibly affixed with another portion of the housing, which other portion is part of the body of the material dispenser. For example, the housing may be reversibly affixed with the material dispenser. For example, the housing may be part of the material dispenser. The housing may be configured to accommodate (e.g., house) the agitation black hole. The housing may be configured to accommodate agitation (vibration) damping controller(s). [0317] In some embodiments, the layer dispenser comprises, or is operatively coupled with, an agitation black hole, e.g., an ABH. The agitation black hole (e.g., ABH) can be configured to (A) (e.g., significantly) reduce agitation (e.g., vibration and/or acoustic radiation) in the panel, (B) have a relatively low reflection coefficient at the location of the agitation black hole, (C) localize agitation, and/or (D) localized trapped agitation modes. The agitation black hole may comprise a portion of the panel (e.g., the second portion of the panel) that has an inhomogeneity. The inhomogeneity may be continuous. The inhomogeneity may cause the agitation to dissipate and/or dampen, e.g., and to (e.g., substantially) cease. The inhomogeneity may be physical and/or chemical. The physical inhomogeneity may comprise structural inhomogeneity. For example, the agitation black hole may comprise a portion of the panel (e.g., the second portion of the panel) that tapers towards an end of the panel. The tapering may be symmetric or asymmetric with respect to a length of the panel. The tapering may be to a (e.g., substantially) vanishing thickness of the panel. The second portion of the panel (e.g., the inhomogeneous portion) may contact an agitation absorber. The agitation absorber may be an elastic material, e.g., a viscoelastic material. The agitation absorber may enhance the agitation loss factors of the second panel portion, e.g., of the inhomogeneous panel portion. The agitation black hole may be configured to trap the agitative energy conveyed to the agitation black hole through the agitation conduction portion of the panel (e.g., the first panel portion).

[0318] Fig. 34 depicts a top perspective view example of a material dispensing mechanism comprising a panel having a first portion disposed (e.g., substantially) horizontally and a second portion disposed (e.g., substantially) vertically, the first portion begin coupled with the second portion by a third portion 3414 that is bent. The second portion is disposed in a housing having a first housing portion 3401 coupled with a second housing portion 3403. The housing comprises a wedge 3402 pressed onto the second portion having a diminishing width, e.g., to generate an agitation black hole (e.g., an ABH). The housing is coupled with a body of the material dispenser at least in part by using coupler 3415. Material dispensing mechanism 3400 includes a first reservoir 3405 optionally configured to direct pre-transformed material (now shown) through a volume of the reservoir 3405 to the exit port 3404 of material dispensing mechanism 3400. The pre-transformed material can be a particulate material. Material dispensing mechanism 3400 includes second reservoir 3406 optionally configured to direct pre-transformed material (not shown) through a volume of the reservoir 3406 to the exit port 3404 of material dispensing mechanism 3400. The first portion of the panel (not shown) can be oriented with respect to the exit port 3404 such that a planar portion of surface of panel 3414 may face exit port 3404 such that during use it is aligned perpendicularly along gravitational vector 3490 pointing towards the gravitational center of the ambient environment. Material dispenser 3400 comprises, or is coupled with, an agitation transducer 3410 configured to induce agitation (e.g., vibrations such as ultrasound vibrations) in the panel, e.g., in an end of the panel. Agitation generator (e.g., transducer) 3410 is coupled by coupler 3408 (e.g., wiring) to a power source (e.g., electrical source). Agitation transducer 3410 is secured and/or aligned by harness 3411 to the body of material dispenser 3400. The body of material dispenser 3400 comprises couplers 3409a and 3409b configured to couple to a mount (not shown). The mount may be configured to facilitate translation of material dispenser 3400 along a lateral direction 3420a-c. The mount may be similar to carriage 1501 of Fig. 15. The mount may be configured to facilitate translation of material dispenser at least in part by being coupled with a carriage and/or an actuator. The lateral translation may be a reversible back and forth lateral translation. Agitation transducer 3410 is coupled to the first portion of the panel at coupling location 3412. Material dispenser 3400 comprises optional bumper 3413 configured to hinder lateral agitation of the first portion of the panel.

[0319] Fig. 34 depicts a bottom perspective view example of a material dispensing mechanism comprising a panel having a first portion 3464a disposed (e.g., substantially) horizontally and a second portion disposed (e.g., substantially) vertically, the first portion 3464a begin coupled to the second portion by a third portion 3464b that is bent. The second portion is disposed in a housing having a first housing portion 3451 coupled with a second housing portion 3453. The housing is coupled with a body of the material dispenser at least in part by using coupler 3465. Material dispensing mechanism 3450 includes reservoir(s) configured to guide the pretransformed material to an exit port aligned with the first portion of the panel. Material dispenser 3450 comprises, or is coupled with, an agitation transducer 3460 configured to induce agitation (e.g., vibrations such as ultrasound vibrations) in the panel, e.g., in an end of the panel.

Agitation transducer 3460 is coupled by coupler 3458 (e.g., wiring) to a power source (e.g., electrical source). Agitation transducer 3460 is secured and/or aligned by harness 3461 to the body of material dispenser 3450. The body of material dispenser 3450 comprises couplers 3459a and 3459b configured to couple to a mount (not shown). The mount may be configured to facilitate translation of material dispenser 3450 along a lateral direction. The mount may be configured to facilitate translation of material dispenser at least in part by being coupled with a carriage and/or an actuator. The lateral translation may be a reversible back and forth lateral translation. Agitation transducer 3460 is coupled to the first portion 3464a of the panel at coupling location 3462. Material dispenser 3450 is devoid of the optional bumper configured to hinder lateral agitation of the first portion of the panel.

[0320] In some embodiments, the material dispenser may be configured to affect a reservoir of the starting material. The material dispenser may be configured to press onto a valve to (e.g., reversibly) alter a position of the valve, e.g., from one position not another position. For example, from a closed position to an open position, or vice versa. The material dispenser may have a lever that toggles a valve. The lever may affect inflow of the starting material into the material dispenser from a reservoir, e.g., a hopper. The material dispenser (e.g., recoater) can be configured to push open a (e.g., gate) valve. The material dispenser may comprise or more reservoir configured to receive starting material to be dispensed by the material dispenser through the exit port, e.g., to be supported by a build plate. The material dispenser may have a first optional reservoir and a second optional reservoir. At least one of the first and second reservoirs may allow flow of the material to the exit opening of the material dispenser, e.g., to dispense the material towards a build plate. During a dispense operation, the starting material flows towards the exit opening from at least one of the first and second reservoirs of the material dispenser. The first and second reservoir may be separated by a partition, the partition may comprise, or be operatively coupled with, the lever. At least one of the reservoir occupies (I) an empty space ready to accept the starting material, (II) an insert that prevents a starting material from coming in. The insert may be solid or hollow. For example, the insert may comprise a hollow cavity. At least one of the reservoirs may be configured to catch material straying from the intended path into the exit channel and through the exit port (e.g., exit opening) of the material dispenser. The material dispenser may be configured to receive incoming starting material from its top and/or from its side, e.g., top side corner. The starting material may flow into the exit channel ending with the exit port, the flow of material may be directly or through a reservoir of the material dispenser. The reservoir may have a slanted side wall(s), or may have non-slanted side wall(s). In an example, the side wall(s) of the reservoir may be (e.g., substantially) parallel to the side wall(s) of the exit channel.

[0321] Fig. 35 depicts vertical cross sectional example of a material dispensing mechanism portion comprising a panel 3505. Material dispensing mechanism 3500 includes a first reservoir 3501 optionally configured to direct pre-transformed material (now shown) through a volume of reservoir 3501 to channel 3530 ending by an exit port. The pre-transformed material can be a particulate material. Material dispensing mechanism 3500 includes a second reservoir optionally configured to direct pre-transformed material (not shown) through a volume of the second reservoir along dotted line 3502 towards exit channel 3530 ending by the exit port. First reservoir 3501 and second reservoir 3502 are separated by partition (e.g., separator) 3503. The separator may comprise a lever that can affect status of a valve (e.g., toggle the valve) when contacting any of its sides 3532a and/or 3532b on translating the material dispenser to the requisite position. The requisite position affecting the valve may be in an ancillary chamber (e.g., Fig. 10, 1054). The ancillary chamber may be separate from the processing chamber, e.g., by a partition such as a door. Material dispensing mechanism 3500 comprises a first body side 3504a and a second body side 3504b separated by a (horizontal) gap from first body side 3504a to form the channel 3530 ending at the exit port. Material entering channel 3530 exist through an exit portion of channel 3530 and onto a panel 3505 that is aligned with the exit port, e.g., the alignment being (e.g., substantially) along the environmental gravitational vector 3590 pointing towards the gravitational center of the ambient environment. During operation, material exiting channel 3530 is spilled from panel 3505, e.g., along directions 3506a and 3506b. Spillage of the material from panel 3505 may be induced by agitating (e.g., vibrating) panel portion 3505. Panel 3505 is separated from each of first sides 3504a and 3504b by a (vertical) gap. Material dispenser 3500 is configured to trap straying starting material from spilling out of the material dispenser. For example, volume having cross section 3531 can facilitate trapping any stray starting material that did not follow path 3502 to the exit opening. The volume 3531 can extend further and include, e.g., the volume up to about line 3533.

[0322] Fig. 35 depicts a top perspective view example of a material dispensing mechanism comprising a panel having a first portion 3555 disposed (e.g., substantially) horizontally and a second portion disposed (e.g., substantially) vertically. The second portion is disposed in a housing having a first housing portion 3561 coupled with a second housing portion 3563. The housing is coupled with a body of the material dispenser at least in part by using coupler 3565. Material dispensing mechanism 3550 includes a first reservoir 3571 optionally configured to direct pre-transformed material (now shown) through a volume of the reservoir 3571 to channel 3470 ending by an exit port. The pre-transformed material can be a particulate material. Material dispensing mechanism 3550 includes a second reservoir optionally configured to direct pretransformed material (not shown) through a volume of the second reservoir along dotted line 3552 towards exit channel 3570 ending by an exit port. Material dispensing machines 3550 comprises a first body side 3554a and a second body side 3554b separated by a (horizontal) gap from first body side 3554a to form channel 3570 ending in an exit port, the channel being elongated along direction 3572 that is (e.g., substantially) perpendicular to the direction of movement of material dispenser 3550 during its material dispensing operation. Material entering channel 3570, exists through an exit portion of channel 3570 and onto a first portion 3555 of the panel that is separated from the exit opening by a (vertical) gap. The panel is aligned with the exit port, e.g., the alignment being (e.g., substantially) along the environmental gravitational vector 3590 pointing towards the gravitational center of the ambient environment. During operation, material exiting channel 3570 is spilled from panel portion 3555, e.g., along directions 3556a and 3556b. Spillage of the material from panel portion 3555 may be induced by agitating (e.g., vibrating) panel portion 3555. Panel portion 3555 is separated from each of first sides 3554a and 3554b by a (vertical) gap.

[0323] Fig. 36 shows an example of a portion of a material dispensing mechanism comprising a first portion 3614a of a panel disposed (e.g., substantially) horizontally during operation, a third portion 3614c of the panel coupling with the first portion 3614a and with a second portion 3614b of the panel disposed (e.g., substantially) vertically. Third portion 3614c is curved. Third portion 3614c and the first portion 3614a have a (e.g., substantially) constant dimensions along their length (e.g., thickness, width, and volume), while second portion 3614b tapers away as the third portion extends away from the second portion (and from the first portion) along the length of the third portion and away from contacting the third portion 3614c. The tapering is asymmetric with respect to the vertical axis, the tapering comprising diminishing width in the direction of 3630. The tapered second portion 3614b is held by elastomer portions 3602a and 3602b that can be of the same material, or of different materials. The elastomer portions 3602a and 3602b can be joined to a single portion. Second portion 3614b is held in a housing having a first portion 3601 and a second portion 3603. The housing includes insert 3604. Insert 3604 can be part of, or separate from, housing portion 3601. Insert 3604 can be of the same material, or of different material, from hosing portion 3601. The housing (e.g., housing portion 3603) is coupled to the body of the material dispenser using coupler 3615. The material dispenser has channel 3625 ending in an exit port, the channel 3625 is configured to allow material to be dispensed therethrough and towards first portion 3614a of the panel. First portion 3614a of the panel may be agitated during use, e.g., to facilitate (controlled) flow of the material off the first portion 3614a of the panel.

[0324] Examples. The following are illustrative and non-limiting examples of methods of the present disclosure.

[0325] Example 1 : In a processing chamber, Titanium powder having an average diameter of 37 micrometers was dispensed by a layer dispensing mechanism (e.g., recoater), the powder being dispensed above a build plate having a diameter of about 315 mm to form a powder bed. A layer dispensing mechanism was used to form a powder bed. When idle, a layer dispensing mechanism is parked in an ancillary chamber (e.g., garage) coupled with the processing chamber in which the build plate was disposed, the ancillary chamber separated from the processing chamber by a door. The layer dispensing mechanism comprised a powder dispenser and a powder remover. The powder remover was configured to attract a portion of the dispensed powder to form a planar exposed surface of the powder bed using vacuum. The attracted powder was conveyed using a material (e.g., powder) conveyance system for recycling and reuse in by the layer dispensing mechanism. The atmosphere in the material conveyance system was similar to the one used in the processing chamber. The processing chamber was under an atmosphere that is less reactive with the powder than the ambient atmosphere external to the processing chamber. The internal processing chamber atmosphere comprised argon, oxygen, and humidity. The oxygen was at a concentration of at most about 1000 ppm, and the humidity had a dew point from about -55°C to about -15°C. The internal processing chamber atmosphere had a pressure of about 16 KPa above atmospheric pressure (e.g., above about 101 KPa), and was at ambient temperature. The processing chamber was equipped with two optical windows made of sapphire in a configuration similar to the one depicted in Fig. 11 e.g., 1118. Each laser beam was guided by an optical setup in an optical system enclosure, the optical system enclosure disposed above the processing chamber, the optical system enclosure comprising a galvanometer scanner. Each of the laser beams originated from a fiber laser and traversed its respective optical window into the processing chamber to impinge on an exposed surface of the powder bed to print layerwise a 3D object. Each of the laser beam had a maximum power of about one (1) Kilo Watt, and a wavelength of about 1060 nanometers. A user was able to view the laser beams during printing using three circular viewing window assemblies similar to Fig. 33, 3302. The viewing assembly comprises a reflective coating facing the interior of the processing chamber. The layer dispensing mechanism formed a powder bed by sequential layerwise deposition, the powder bed being disposed in a build module above the build plate. The layer dispensing mechanism (e.g., recoater) included a powder dispensing mechanism (e.g., dispenser) and a powder removal mechanism (e.g., remover). The powder removal mechanism was similar to the one disclosed in fig. 14, 1470; and fig. 15. The powder dispenser mechanism was similar to the one disclosed in figs. 34-36, lacking the optional bumper 3413. The layer dispensing operation included (1) using the powder dispensing mechanism to dispense a planar layer having an average height of about 250 micrometers, followed by (2) using the powder removal mechanism to remove about 200 micrometers from the deposited layer, resulting in a layer having an average height of about 50 micrometers. In the powder dispensing operation, powder flowed in the direction 3502 towards the exit opening of the dispenser, with the portion 3501 being empty. The vibration generator generated ultrasound waves at a frequency of about 40 kilohertz continuously during layer dispensing. The layer dispenser dispensed a planar layer of the powder in about 10 seconds. The layer dispenser dispensed layers at a rate of 2 milliliters per second (mL/s). The average planarity of the layer had an error of at most about 20% from the thickness of the layer. The planarity of the layer had a Sa value of at most 50 micrometers for a 250 micrometer thick layer. The arithmetical mean height (Sa) is a roughness parameter defined as the mean of the absolute value of the height of points within the defined area. The layer dispenser dispensed planar layers of powder at a rate of about 2 milliliters of powder per second (mL/s). In the powder removal operation, the powder was removed using a vacuum source connected to exit port similar to 1503, the powder entering nozzle similar to the one depicted in example 1470, into cavity similar to 1502 and out of the powder removal mechanism (e.g., cavity thereof). The build plate was disposed above a piston. The build plate traversed down at increments of about 50 .m at a precision of +/-2 micrometers using an optical encoder. The powder bed was used for layerwise printing a 3D object using the lasers. The removed powder was recycled using a recycling system as part of the powder recycling system that is part of the material conveyance system. The recycled powder was reused by the layer dispensing mechanism, e.g., recoater. [0326] While preferred embodiments of the present invention have been shown, and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations, or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the invention described herein might be employed in practicing the invention. It is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations, or equivalents. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A device for generating a planar layer of powder material, the device comprising: a dispenser comprising (I) a reservoir configured to accommodate powder material and (II) an exit port, the dispenser being configured to dispense at least a first portion of the powder material through the exit port; and an agitator that is operatively coupled to, or that is part of, the dispenser, the agitator being configured to induce an increase of a flow rate of the powder material from the exit port of the dispenser towards a target surface, the device being configured to generate a first layer of powder material on the target surface, the first layer having a first exposed surface that is substantially planar according to a first central tendency of planarity, and the first layer having a second central tendency of a thickness, wherein:

(A) the target surface includes one or more protrusions from the target surface, the one or more protrusions being of one or more three-dimensional objects, and wherein the second central tendency of the thickness of the first layer is smaller than a maximal height of the one or more protrusions from the target surface,

(B) the device further comprises a remover configured to remove a second portion of powder material from the first layer to generate a second layer of powder material having a second exposed surface that is substantially planar according to a third central tendency of planarity, the third central tendency of planarity being of the same type as the first central tendency of planarity, and wherein the third central tendency of planarity is smaller than the first central tendency of planarity of the first layer such that the third central tendency of planarity is indicative of a more planar surface than the first tendency of planarity,

(C) the second layer has a thickness having a fourth central tendency of thickness of the same type as the second central tendency of thickness, wherein during operation of the device, a closest distance between the target surface and the device is larger than (a) the second central tendency of thickness of the first layer and/or (b) the fourth central tendency of thickness of the second layer,

(D) the agitator is separated from the dispenser,

(E) the agitator is operatively coupled to a panel that is operatively coupled to, or that is part of, the dispenser, the panel being arranged with respect to the exit port of the dispenser, the panel being configured to (c) in the first operating state, restrict flow of the powder material through the exit port of the dispenser and (d) in the second operating state, allow the flow of the powder material from the exit port of the dispenser towards the target surface,

(F) a transducer of the agitator is disposed outside of a processing chamber that encloses the first layer, (G) the device is configured to operate at an interior atmosphere of the processing chamber, and wherein the a dew point of an interior atmosphere of the processing chamber is (III) above a level of humidity at or below which the powder material agglomerates, and (IV) below a level in which the powder material absorbs water (e) such that the powder material becomes reactive under conditions of a three-dimensional printing process utilizing the powder material and/or (f) such that the absorbed water on the powder material is sufficient to cause a measurable defect in the one or more three-dimensional objects printed from the powder material, or

(H) any combination of (A)-(G).

2. The device of claim 2, wherein the device is configured to operatively coupled to a recycling system that (i) recycles at least a fraction of the second portion of powder material removed by the remover and/or (ii) provides at least a portion of the powder material utilized by the dispenser.

3. The device of claim 2, wherein the first central tendency of planarity and the second central tendency of planarity are each measured as mean, median, or mode.

4. The device of claim 2, wherein the first central tendency of planarity and the second central tendency of planarity are each a surface roughness measured as (i) an arithmetic average of a surface roughness profile (R_a), (ii) an arithmetic average of peak-to-valley height of a surface roughness profile (R_z), or (iii) a root mean square (RMS) average.

5. The device of claim 2, wherein the third central tendency of thickness and the fourth central tendency of thickness are each measured as mean, median, or mode.

6. The device of claim 2, wherein the third central tendency of thickness and the fourth central tendency of thickness are each measured as (i) an arithmetic average of a surface roughness profile (R_a), (ii) an arithmetic average of peak-to-valley height of a surface roughness profile (R_z), or (iii) a root mean square (RMS) average.

7. The device of claim 2, wherein at least during use of the device, the device is configured for lateral translation along the target surface.

8. The device of claim 2, wherein the agitator is configured to increase the flow at least in part by allowing the flow.

9. The device of claim 2, wherein the agitator is configured to restrict the flow at least in part by stopping the flow.

10. The device of claim 2, wherein the agitator is configured for mechanical and/or sonic agitation.

11 . The device of claim 2, wherein the target surface is an exposed surface of a powder bed in which the one or more three-dimensional objects were generated, and wherein the device is configured to dispense the planar layer on the exposed surface of the powder bed.

12. The device of claim 2, wherein the powder material comprises elemental metal, metal alloy, a ceramic, or an allotrope of elemental carbon.

13. The device of claim 2, wherein the device is configured to operatively couple to an energy source configured to generate an energy beam utilized in printing the one or more three- dimensional objects using three-dimensional printing.

14. The device of claim 2, wherein the increase of the flow rate comprises an increase of at least about 0.2 cubic centimeters per second.

15. The device of claim 2, wherein the reservoir is configured to retain powder material.

16. The device of claim 2, wherein in the first operating state, the agitator is configured to induce the increase of the flow rate of the powder material from a zero, or a substantially zero, flow rate.

17. The device of claim 2, wherein in the second operating state, the agitator is configured to cease, or substantially cease, inducing the flow rate of the powder material through the exit port of the dispenser.

18. The device of claim 2, wherein the device is configured to (i) in a first operating state, induce the increase of the flow rate of the powder material from the exit port of the dispenser towards the target surface and (ii) in a second operating state, reduce inducing the flow rate of the powder material through the exit port of the dispenser.

19. The device of claim 2, wherein the second central tendency of the thickness is from about 30 microns to about 500 microns.

20. The device of claim 2, wherein the first central tendency of planarity of the first layer is from about 15% to about 65% of the second central tendency of the thickness.

21 . The device of claim 2, wherein the target surface includes one or more protrusions from the target surface, the one or more protrusions being of the one or more three-dimensional objects, and wherein the second central tendency of the thickness of the first layer is smaller than a maximal height of the one or more protrusions from the target surface.

22. The device of claim 2, wherein the device further comprises a remover configured to remove a second portion of powder material from the first layer to generate a second layer of powder material having a second exposed surface that is substantially planar according to a third central tendency of planarity, the third central tendency of planarity being of the same type as the first central tendency of planarity, and wherein the third central tendency of planarity is smaller than the first central tendency of planarity of the first layer such that the third central tendency of planarity is indicative of a more planar surface than the first tendency of planarity.

23. The device of claim 2, wherein the second layer has a thickness having a fourth central tendency of thickness of the same type as the second central tendency, wherein during operation of the device, the closest distance between the target surface and the device is larger than (a) the second central tendency of thickness of the first layer and/or (b) the fourth central tendency of thickness of the second layer.

24. The device of claim 2, wherein the agitator is separated from the dispenser.

25. The device of claim 2, wherein the agitator is operatively coupled to the panel that is operatively coupled to, or that is part of, the dispenser, the panel being arranged with respect to the exit port of the dispenser, the panel being configured to (c) in the first operating state, restrict flow of the powder material through the exit port of the dispenser and (d) in the second operating state, allow the flow of the powder material from the exit port of the dispenser towards the target surface.

26. The device of claim 2, wherein the transducer of the agitator is disposed outside of the processing chamber enclosing the first layer.

27. The device of claim 2, wherein the device is configured to operate at an interior atmosphere of the processing chamber, and wherein the dew point of the interior atmosphere of the processing chamber is (III) above the level of humidity at or below which the powder material agglomerates, and (IV) below the level in which the powder material absorbs water (e) such that the powder material becomes reactive under conditions of the three-dimensional printing process utilizing the powder material and/or (f) such that the absorbed water on the powder material is sufficient to cause the measurable defect in the three-dimensional object printed from the powder material.

28. An apparatus for generating a planar layer of powder material, the apparatus comprising at least one controller configured to (i) operatively couple to the device of any of claims 1 to 27; and (ii) direct the device to implement at least one operation associated with the device comprising direct the device to generate the planar layer.

29. Non-transitory computer readable program instructions that, when executed by one or more processors operatively coupled to the device of any of claims 1 to 27, implement one or more operations associated with the device comprising directing the device to generate the planar layer.

30. A method for generating a planar layer of powder material, the method comprising: providing the device of any of claims 1 to 27; and performing one or more operations associated with the device comprising using the device to dispense the planar layer.

31 . A system for three-dimensional printing, the system comprising: the device of any of claims 1 to 27 configured to generate a planar layer of powder material; and an energy beam configured to irradiate the planar layer of the powder material to print at least a portion of at least one three-dimensional object at least in part by using three-dimensional printing.