Extrudes the filament, creating your model. The standard nozzle for an Original Prusa FFF printer is a 0.4mm brass nozzle, for 1.75mm filament. This can be replaced with virtually any E3D-compatible nozzle, for 1.75mm filament. Different sizes and types are available, e.g. 0.25mm or 0.6mm, and hardened steel nozzles to print abrasive filaments.