In SLS, a laser selectively sinters the particles of a polymer powder, fusing them together and building a part layer-by-layer. The materials used in SLS are thermoplastic polymers that come in a granular form.

During the 3D printing process, the SLS machine preheats the bulk powder material in the powder bed somewhat below its melting point, to make it easier for the laser to raise the temperature of the selected regions the rest of the way to the melting point. A roller will apply a layer of polymer powder, then the laser will sinter the powder according to the 3D file and the build platform will lower before applying a new layer of powder. The process will be repeated until the desired part is created. 

Multi Jet Fusion is a powder-based technology but does not use lasers. The powder bed is heated uniformly at the outset. A fusing agent is jetted where particles need to be selectively molten, and a detailing agent is jetted around the contours to improve part resolution. While lamps pass over the surface of the powder bed, the jetted material captures the heat and helps distribute it evenly.

The process continues layer-by-layer until a complete part is formed. After the print is finished, the build unit with the material and parts are rolled onto a processing station for cooling and powder excavation SLS & MJF does not require support structures because unsintered powder surrounds the parts during printing. SLS printing can produce previously impossible complex geometries, such as interlocking or moving parts, parts with interior components or channels, and other highly complex designs.

SLS & MJF can take generative design to its full potential by enabling lightweight designs that employ complex lattice structures impossible to manufacture with traditional methods.