OpenSCAD is a free CAD software for creating solid 3D models. Unlike most free 3D modeling software, it doesn’t focus on the artistic aspects of 3D modeling but instead on the CAD aspects. OpenSCAD works like a 3D-compiler that reads in a script file that describes the object and renders the 3D model from the script file. This way of working gives you full control over the modeling process. It also enables you to easily change any step in the process or make designs that are defined by configurable parameters. It might be the perfect application for you if you are planning to create 3D models of machine parts.