With FDM technology it is possible to process a wide range of thermoplastic polymers, among which the most common are PLA, ABS, NYLON or PET. Materials such as TPU have elastomeric characteristics allowing flexible parts to be printed. On the most performing machines it is also possible to print engineering polymers such as PEEK and PEI. Water-soluble support materials such as PVA can be used. There are some filaments in composite material, consisting of a polymer matrix and loaded with fibers (Example: Nylon filled carbon fiber or fiberglass). There are filaments with metal charge, which are printed as normal materials, which require a post sintering process in which the thermoplastic matrix evaporates leaving completely metallic parts.
The materials are commonly marketed in the form of filament spools (standard diameter 1.75mm or 2.85mm). Some machines, especially large format machines, use polymers in the form of pellets, much cheaper, and in some cases deriving from plastic recycling.