Selective layer sintering (SLS) uses powdered material as input, selectively fusing particles, layer by layer. 3D objects printed using SLS are very dense and have very high stability. The surface quality is decent, but can be polished and coated with varnish. The most common material used with SLS is PA (polyamide), which can also be infused with aluminum, glass, or carbon fiber, resulting in better wear or chemical resistance. This 3D plastic printing technology is great for spare parts, prototypes, and functional components.