OpenSCAD – Free CAD Software
OpenSCAD is free CAD software for creating solid 3D CAD objects. It is available for Linux/UNIX, MS Windows and Apples OS X.
Unlike most free software for creating 3D models it does not focus on the artistic aspects of 3D modeling but instead on the design aspects. Thus it might be the application you are looking for when you are planning to create 3D models of machine parts but pretty sure is not what you are looking for when you are more interested in creating computer-animated movies.
OpenSCAD is not an interactive modeler. Instead it is something like a 3D-compiler that reads in a script file that describes the object and renders the 3D model from this script file. This gives the designer full control over the modeling process and enables you to easily change any step in the modeling process or make designers that are defined by configurable parameters.
OpenSCAD provides two main modeling techniques: First there is constructive solid geometry (aka CSG) and second there is extrusion of 2D outlines. As data exchange format for this 2D outlines AutoCAD DXF files are used. In addition to 2D paths for extrusion it is also possible to read design parameters from DXF files. Besides DXF files OpenSCAD can read and create 3D models in the STL and OFF file formats.
Vendor: Clifford Wolf and Marius Kintel
Tutorials available on site.