Abstract: A system for forming a multiple layer object, the system including: a spreader to form a layer of polymer particles, the polymer particles having a melting temperature (Tm) of at least 250° C.; a fluid ejection head to selectively deposit a first fusing agent on a first portion of the layer and selectively deposit a second fusing agent on a second portion of the layer, wherein the fluid ejection head does not deposit the fusing agent on a third portion of the layer; and a heat source to heat the first portion and second portion, wherein the first portion is part of the multiple layer object and the second portion is not part of the multiple layer object and the second portion raises a temperature of polymer particles in a subsequent layer.

Abstract: The present disclosure relates to a method of three-dimensional (3D) printing a 3D printed metal object. The method comprises selectively jetting an alloying agent onto build material. The build material comprises a first metal and the alloying agent comprises an alloying component that forms an alloy with the first metal. The method also comprises selectively jetting a binding agent onto the build material; binding the build material to form a layer: the alloying component is incorporated in the 3D object in a predetermined arrangement that comprises a first and a second region. The first region comprises the alloying component and the second region is substantially free from the alloying component or comprises the alloying component at a lower concentration than the first regions. The disclosure also relates to a kit that may be used in the method and a 3D printed structure that may be formed using the method.

Abstract: According to an example, an apparatus may include an agent delivery device to selectively deliver an agent onto a layer of build material particles. The apparatus may also include an energy source to apply energy onto the layer of build material particles to selectively fuse the build material particles in the layer based upon the locations at which the agent was delivered and a chamber formed of a plurality of walls, in which the agent delivery device and the energy source are housed inside the chamber. The apparatus may further include a vapor source to supply vapor into the chamber to wet the build material particles inside the chamber.

Abstract: A system for forming a multiple layer object, the system including: a spreader to form a layer of polymer particles, the polymer particles having a melting temperature (Tm) of at least 250° C.; a fluid ejection head to selectively deposit a first fusing agent on a first portion of the layer and selectively deposit a second fusing agent on a second portion of the layer, wherein the fluid ejection head does not deposit the fusing agent on a third portion of the layer; and a heat source to heat the first portion and second portion, wherein the first portion is part of the multiple layer object and the second portion is not part of the multiple layer object and the second portion raises a temperature of polymer particles in a subsequent layer.

Abstract: An example of a fusing agent includes a metal bis(dithiolene) salt, a polar aprotic solvent, and a balance of water. An example of a method for making an example of the fusing agent includes adding a metal bis(dithiolene) salt into a liquid vehicle including at least a polar aprotic solvent and water.

Abstract: In some examples, a distribution of values of a property of a given layer to be printed as part of three-dimensional (3D) printing is predicted, wherein the predicting is based on a distribution of values of the property in a previous layer that has been printed as part of the 3D printing. 3D printing of an object is controlled based on the predicted distribution of values of the property of the given layer.

Abstract: A device includes a coater, a dispenser, and a treatment portion. The coater is to coat, layer-by-layer, a build material relative to a build pad to form a 3D object. The dispenser is to at least dispense a fluid including a first at least potentially electrically conductive material. In at least some selected locations of an external surface of the 3D object. The treatment portion is to treat the 3D object to substantially increase electrically conductivity on the external surface of the 3D object at the at least some selected locations.

Abstract: A kit for three-dimensional printing a metal object is described. The kit comprises a build material and a shaping composition. The build material comprises metallic particles. The shaping composition comprises a metallic mixture for forming an intermetallic compound with the metallic particles and/or that is exothermically reactive.

Abstract: In an example of a method for three-dimensional (3D) printing, a build material composition is applied to form a build material layer. The build material composition includes a polyamide. The polyamide is selectively melted, based on a 3D object model, in at least a portion of the build material layer to form a molten portion including molten polyamide. An epoxy agent is selectively applied, based on the 3D object model, on the molten portion of the build material layer. The epoxy agent includes a polyfunctional epoxy, which crosslinks the molten polyamide in the molten portion.

Abstract: Fusing agent(s) are described herein. In an example, a fusing agent can comprise a metal bis(dithiolene) complex, at least one electron donor compound, a polar aprotic solvent, and water. In some examples, the at least one electron donor compound can comprise at least one hindered amine light stabilizer compound. In some examples, the polar aprotic solvent can be selected from the group consisting of 1-methyl-2-pyrrolidone, 2-pyrrolidone, 1-(2-hydroxyethyl)-2-pyrrolidone, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and a combination thereof.

Abstract: In an example implementation, a method of printing a multi-structured three-dimensional (3D) object includes forming a layer of sinterable material. The method includes processing a first portion of the sinterable material using a first set of processing parameters and processing a second portion of the sinterable material using a second set of processing parameters. The processed first and second portions form, respectively, parts of a first and second structure of a multi-structured 3D object.

Abstract: Apparatus and methods for making metal-connected particle articles. A metal containing fluid is selectively applied to a layer of particles. The metal in the fluid is used to form metal connections between particles. The metal connections are formed at temperatures below the sintering temperature of the particles in the layer of particles.

Abstract: According to examples, an apparatus may include a printhead assembly containing a housing supporting a printhead. The printhead may have nozzles that are to fire droplets of a functional agent onto a layer of build material particles along respective flight paths to form sections of a 3D object from the build material particles, an array of light emission devices to direct respective light beams in the respective flight paths, and an array of photon detectors to detect respective light beams directed from a light source of the array of light emission devices, the light emission devices and the photon detectors being supported on the housing. The apparatus may also include a controller to determine whether any of the nozzles is operating improperly based upon whether the photon detectors detected the light beams and to output an instruction regarding an improperly operating nozzle in response to a determination that the nozzle is operating improperly.

Abstract: In some examples, at least one agent distributor may be to selectively deliver mixtures of coalescing agent and carrier onto portions of a layer of build material at variable coalescing agent concentrations and variable contone densities. A controller may be to control the at least one agent distributor to selectively deliver the mixture to a portion of the layer at a selected coalescing agent concentration and a selected contone density.

Abstract: According to an example, an apparatus may include an agent delivery device to selectively deliver an agent onto a layer of build material particles. The apparatus may also include an energy source to apply energy onto the layer of build material particles to selectively fuse the build material particles in the layer based upon the locations at which the agent was delivered and a chamber formed of a plurality of walls, in which the agent delivery device and the energy source are housed inside the chamber. The apparatus may further include a vapor source to supply vapor into the chamber to wet the build material particles inside the chamber.

Abstract: According to an example, an apparatus may include a memory that may store instructions to cause a processor to generate, for each part to be fabricated in a build envelope of a 3D fabricating device, first level descriptions and second level descriptions for the part. The processor may determine, using the first level descriptions, whether there is an arrangement that results in the parts jointly fitting within the build envelope while providing certain thermal decoupling spaces between the parts. In response to a determination that the arrangement using the first level descriptions for the parts has not been determined, the processor may determine, using the second level descriptions, whether there is an arrangement that results in the parts jointly fitting within the build envelope while providing the certain thermal decoupling spaces.

Abstract: In one example in accordance with the present disclosure, a system is described. The system includes a reader to read an identifier associated with a part. An extractor of the system extracts, based on the identifier, a design file for the part. A modifier of the system receives user input modifying the design file and a transmitter transmits the modified design file for production of the part.

Abstract: A 3D printing kit can include a powder bed material comprising from about 80 wt % to 100 wt % polymer particles, a fusing agent to selectively apply to the powder bed material, and a hardener to selectively apply to the powder bed material. The polymeric particles can include a polyalkylene backbone with both ethylene and propylene polymerized monomeric units with from 2 mol % to 15 mol % of the polymerized monomeric units include a grafted side chain having an epoxide moiety. The fusing agent can include water and a radiation absorber that absorbs electromagnetic energy and converts the electromagnetic energy to heat. The hardener can be present in the fusing agent or can be included in a hardening agent that is separate from the fusing agent.

Abstract: Apparatus and methods for making metal-connected particle articles. A metal containing fluid is selectively applied to a layer of particles. The metal in the fluid is used to form metal connections between particles. The metal connections are formed at temperatures below the sintering temperature of the particles in the layer of particles.

Abstract: In one example in accordance with the present disclosure, a system is described. The system includes a scanner to read three-dimensional (3D) print information from a storage element to be embedded in a 3D printed object. The system also includes a controller. The controller 1) instructs an additive manufacturing device to form the 3D printed object based on the 3D print information stored in the storage element and 2) embeds the storage element into the 3D printed object.