3D printing using FDM essentially implies that the object being printed is fused together by printing layer after layer in a certain pattern. Objects are created by extruding layer upon layer of the heated material on the build tray or printing bed of the 3D printer. FDM 3D printers use a filament of certain material, usually plastic, which is passed through a hot end, to melt. The melted filament material is used to make layers which are then fused together to give the object its final shape. A wide variety of materials can be used for FDM 3D printing like plastics, pastes and some metals as well.