Abstract: According to examples, an apparatus may include an array of micro-mirrors, each of the micro-mirrors being individually controllable to selectively be in a first position or a second position, and a light source to direct a pulse of light onto the array of micro-mirrors with sufficient intensity to cause micron-sized particles on a powder bed upon which the light is directed from the array of micro-mirrors to at least partially melt. Each of the micro-mirrors that is in the first position may reflect light onto a respective area on a layer of micron-sized particles to at least partially melt the micron-sized particles in the respective area and each of the micro-mirrors that is in the second position may reflect light away from the powder bed on which the micron-sized particles are supported.

Abstract: The present disclosure is drawn to a material set including a powder bed material and a binder fluid. The powder bed material can be from 80 wt % to 100 wt % metal particles having a metal core and a thin metal layer on the core, and the metal particles having a D50 particle size distribution value ranging from 4 ?m to 150 ?m and the thin metal layer having an average thickness from 20 nm to 2 ?m. The binder fluid can adhere a first portion of the powder bed material relative to a second portion of the powder bed material not in contact with the binder fluid.

Abstract: According to an example, an apparatus may include a heating lamp to illuminate and heat an area of a layer of build materials, in which the build materials may be one of a metallic and a plastic powder. The apparatus may also include a laser source to generate a laser beam and a controller to control the heating lamp to heat the build materials in the area of the layer of build materials to a temperature that is between about 100° C. to about 400° C. below a temperature at which the build materials begin to melt and to control the laser source to output a laser beam to melt the build materials in a portion of the heated area of the layer of build materials.

Abstract: The present disclosure is drawn to a three-dimensional printing system can include a powder bed material, including from 80 wt % to 100 wt % metal particles having a D50 particle size distribution value ranging from 5 ?m to 75 ?m and a powder bed support substrate for receiving the powder bed material. The system can also include a fluid ejector operable to digitally deposit a thermally sensitive binder fluid onto a selected portion of the powder bed material on the powder bed support substrate. The thermally sensitive binder fluid can include water, a reducible metal compound, and a thermally activated reducing agent. A light source can also be present to generate a pulse energy sufficient to cause the thermally activated reducing agent to reduce the reducible metal compound and bind metal particles together to form a green three-dimensional part.

Abstract: In an example of a three-dimensional (3D) printing method, a metallic build material is applied. A patterning fluid, including a metal salt, is selectively applied on at least a portion of the metallic build material. Prior to an application of additional build material, the metallic build material is exposed to light irradiation to cause the metal salt to reach a thermal decomposition temperature and thermally decompose to a metal. During the exposing, the metallic build material is maintained below a sintering temperature of the metallic build material.

Abstract: A material set can include a powder bed material including from 80 wt % to 100 wt % metal particles and a thermally sensitive binder fluid. The metal particles can have a D50 particle size distribution value ranging from 5 ?m to 75 ?m. The thermally sensitive binder fluid can include an aqueous liquid vehicle, a reducible metal compound, and a thermally activated reducing agent.

Abstract: In example implementations, a minor assembly for a three dimensional printer is provided. The minor assembly includes a first side and a second side. The first side is symmetrical to the second side and enclose a cylindrical light source. The first side and the second side each include a first curved reflective surface and a second curved reflective surface. An end of the first curved reflective surface and a beginning of the second curved reflective surface form an edge along a surface formed by the first curved reflective surface and the second curved reflective surface.

Abstract: The present disclosure is drawn to material sets for 3D printing and methods of 3D printing. The material set can include a coalescent an organic-soluble near-infrared dye having a peak absorption wavelength from 800 nm to 1400 nm. The coalescent ink can also include water and an organic co-solvent. The material set can also include a particulate polymer formulated to coalesce when contacted by the coalescent ink and irradiated by a near-infrared energy having the peak absorption wavelength.

Abstract: According to an example, in a method, a radiation source that is to output radiation at a preset energy level onto a surface of a three-dimensional (3D) printed object may be activated. In addition, the radiation source may be deactivated after a predefined period of time sufficient to cause an outer portion of about a predetermined thickness of the surface of the 3D printed object to begin to melt to finish the surface of the 3D printed object.

Abstract: A three-dimensional printing kit can include a binder fluid and a particulate build material. The particulate build material can include from about 80 wt % to 100 wt % metal particles that can have a D50 particle size distribution from about 1 ?m to about 150 ?m, wherein the metal particles of the particulate build material can include surface-irradiated metal particles, and wherein the particulate build material can exhibit a water contact angle from 0° to about 25°.

Abstract: To additively manufacture a 3D object, a layer of material is deposited onto a receiving surface. Droplets are selective deposited onto first portions of the layer with at least some droplets including at least a first color agent. A gas discharge illuminant selectively induces a first amount of heating in the first portions of the layer substantially greater than a second amount of heating in second portions of the layer omitting the first color agent.

Abstract: Example described herein include a three-dimensional printer a three-dimensional printing device that includes a fusible material applicator to apply a layer of fusible material, a inhibiting material applicator to apply a patterned layer of inhibiting material to establish exposed regions of the layer of fusible material and blocked regions of the layer of fusible material based on information corresponding to a three-dimensional model, and a photonic energy emitter to apply photonic energy to fuse the exposed regions of the layer of fusible material.

Abstract: According to examples, an apparatus may include a build platform and a chamber. The chamber may support a layer forming station including a spreading component to spread a layer of build material particles onto the build platform and an agent delivery component to apply fusing agent onto selected locations on the spread layer of build material particles and a heating station including a heating component to apply energy onto the spread layer of build material particles and the applied fusing agent, in which the heating station is separated from the layer forming station. The apparatus may also include an actuator to move the chamber with respect to the build platform or vice versa while maintaining the separation between the layer forming station and the heating station.

Abstract: According to examples, an apparatus includes a processor and a memory on which is stored machine readable instructions. The instructions may cause the processor to identify an intended surface property level for a surface of a three-dimensional (3D) object, determine an amount of radiation to be applied as a flash of radiation onto the surface to obtain the intended surface property level, and output the determined amount of radiation to be applied as a flash of radiation, in which a radiation source is to flash apply the determined amount of radiation onto the surface of the 3D object.

Abstract: A system may include a printhead for ejecting a first fluid including a polymer, the ejected first fluid forming a substrate with a thermal conductivity of less than 0.5 W/(m-K); a spreader to spread a layer of metal particulate on the substrate, wherein the printhead further ejects a second fluid, the ejected second fluid masking a portion of the layer of metal particulate on the substrate; and a pulse irradiation light source to fuse an unmasked portion of the layer of metal particulate.

Abstract: A system for forming a part with a support including: a liquid reservoir to hold a support material to form the support; an ejector to receive support material from the liquid reservoir and deposit the support material into a build area; an actuator to provide relative motion between the ejector and the build area; and a spreader to form a layer of metal particles in the build area, wherein the support provides support for the part during sintering.

Abstract: Described herein are methods and systems for printing a three-dimensional object. In an example, a method for printing a three-dimensional object can comprise: (i) a metallic build material being applied; (ii) a binder fluid being applied on at least a portion of the metallic build material; (iii) the selectively applied binder fluid can be flash fused to bind the metallic build material and the selectively applied binder fluid by application of an energy flux having an energy density of from about 0.5 J/cm2 to about 20 J/cm2 for less than about 1 second. In the example, (i), (ii), and (iii) can be repeated at least one time to form the three-dimensional object.

Abstract: According to an example, a three-dimensional (3D) printer may include a delivery device to deposit a light absorbing agent onto selected areas of a layer of build material particles, in which the light absorbing agent absorbs light having wavelengths that are around the ultraviolet wavelength range. The 3D printer may also include a light source to apply light onto the selectively deposited light absorbing agent and the layer of the build material particles, in which the light absorbing agent absorbs light around the ultraviolet wavelength range from the applied light and becomes heated to a temperature that causes the build material particles upon which the light absorbing agent has been deposited to melt and to fuse together following cessation of the application of the light.

Abstract: Example described herein include a three-dimensional printer a threedimensional printing device that includes a fusible material applicator to apply a layer of fusible material, a inhibiting material applicator to apply a patterned layer of inhibiting material to establish exposed regions of the layer of fusible material and blocked regions of the layer of fusible material based on information corresponding to a three-dimensional model, and a photonic energy emitter to apply photonic energy to fuse the exposed regions of the layer of fusible material.

Abstract: The present disclosure is drawn to coalescent inks and material sets, such as for 3D printing. In one example, the coalescent ink can include a conjugated polymer, a colorant imparting a visible color to the coalescent ink, and an ink vehicle comprising a high boiling point co-solvent having a boiling point of 250° C. or greater. The high boiling point co-solvent can be present in an amount from about 1 wt % to about 4 wt % with respect to the coalescent ink.