RepRap ------ The Replicating Rapid Prototyper Project These are the files for the mechanical design of the RepRap polymer extruder head. Version 2. 2 November 2005 http://reprap.org Files with the extension .aoi are for the Art of Illusion design system (http://www.artofillusion.org). Files with the extension .stl are the rapid prototyper files for the extruder components, from which they can be made directly. Files with the extension .dxf are engineering drawings for the open-source version of QCad (http://www.ribbonsoft.com/qcad.html).