Selective Laser Sintering (SLS) is an additive manufacturing technology developed under sponsorship by the Defense Advanced Research Projects Agency (DARPA) and acquired in 2001 by 3D Systems. 

Selective Laser Sintering (SLS) uses high power CO2 lasers (carbon dioxide laser) to fuse plastic, metal or ceramic powder particles together, layer-by-layer, to form a solid model. The system consists of a laser, part chamber, and control system.

The part chamber consists of a build platform, powder cartridge, and leveling roller. A thin layer of build material is spread across the platform where the laser traces a two-dimensional cross section of the part, sintering the material together. The platform then descends a single layer thickness and the leveling roller pushes material from the powder cartridge across the build platform, where the next cross section is sintered to the previous. This process is repeated one slice at a time until the part build height is completed.

Once the model is complete, it is removed from the part chamber and finished by removing any loose material and smoothing the visible surfaces.  Part support is accomplished by the un-sintered powder that surrounds the parts during processing.