 Free and open-source 3-D modeling programs like Blender, OpenSCAD, and FreeCAD are preferred in the RepRap community, but almost any CAD or 3D modeling program can be used with the RepRap, as long as it can produce STL files (slic3r also supports .obj and .amf files).Thus, content creators make use of any tools they are familiar with, whether they are commercial CAD programs, such as SolidWorks and Autodesk AutoCAD, Autodesk Inventor, Autodesk 123D Design, Tinkercad, or SketchUp along with the libre software.RepRaps print objects from ABS, Polylactic acid (PLA), Nylon (possibly not all extruders can), HDPE, TPE and similar thermoplastics.