Abstract: In an example, a method includes operating, by a processor, on object model data. The object model data describes at least part of an object to be generated in additive manufacturing. The method also includes determining, by a processor, pattern data. The pattern data comprising areas of variable reflectance intended to be formed on a portion of the object. The method includes determining, by a processor, object generation instructions to apply a fusing agent to at least part of a layer of build material corresponding to the portion of the object in a density corresponding to the reflectance of the generated pattern data.

Abstract: In an example, a method includes operating, by a processor, on object model data. The object model data describes at least part of an object to be generated in additive manufacturing. The method also includes determining, by a processor, pattern data. The pattern data comprising areas of variable reflectance intended to be formed on a portion of the object. The method includes determining, by a processor, object generation instructions to apply a fusing agent to at least part of a layer of build material corresponding to the portion of the object in a density corresponding to the reflectance of the generated pattern data.

Abstract: The present disclosure is drawn to 3D printing kits and methods of making 3D printed articles. In one example, a 3D printing kit can include a powder bed material, a fusible fluid, and an activator fluid. The powder bed material can include polymer particles. The fusible fluid can include a radiation absorber. The fusible fluid can be to selectively apply to the powder bed material. The activator fluid can include a non-conductive electroless metal plating activator. The activator fluid can also be to selectively apply to the powder bed material.

Abstract: The present disclosure is drawn to 3D printing kits and methods of making 3D printed articles. In one example, a 3D printing kit can include a powder bed material, a fusible fluid, and an activator fluid. The powder bed material can include polymer particles. The fusible fluid can include a radiation absorber. The fusible fluid can be to selectively apply to the powder bed material. The activator fluid can include a non-conductive electroless metal plating activator. The activator fluid can also be to selectively apply to the powder bed material.

Abstract: According to examples, an apparatus may include forming components and a controller to control the forming components to fuse build material particles located in a selected area of a layer of build material particles forming a part section of a 3D object, in which the selected area is within and borders a selected boundary. The controller may also wait for a period of time to allow the part section to shrink to form a shrunken part section and, following the period of time, fuse build material particles located in a certain area around the shrunken part section, in which the certain area occupies a preset distance originating around the selected boundary of the layer of build material particles and extending toward an interior of the part section, and the preset distance corresponds to an amount of shrinkage predicted to occur in the part section during the period of time.