G12 is a large industrial 3D printer based on the FGF (fused granulate fabrication) technology, which is similar to FDM 3D printing and shares the same material extrusion principle. The difference lies in the form of plastics used for printing. While FDM machines print with filaments, FGF 3D printers build parts with granular material, or pellets.

The extrusion screw rotates and melts the pellets into a homogeneous mass which is forced through a nozzle under the pressure. Plastic pellets are the material for producing FDM filaments, so printing directly with granules greatly reduces the production costs.