I just found a 3D CAD software that is released under different FS licences: www.brlcad.org. The Sourceforge page http://sourceforge.net/projects/brlcad says:
BRL-CAD is a powerful constructive solid geometry solid modeling system that includes an interactive geometry editor, ray tracing support for rendering and geometric analysis, network distributed framebuffer support, image and signal-processing tools.
It is released under BSD License, GNU General Public License (GPL), GNU Library or Lesser General Public License (LGPL). Seems good.