K3DCad is a 3D CAD program for KDE2 (Linux) to design black-and-white-depthmaps and 3D stereograms (a la "Magic Eye").
The goal of
GNU CAD is to create a professional, but open-source CAD (Computer Aided Design) Package for linux/unix systems. The system will eventually include a plugin interface as well as scripting capability, possibly through pearl,bash or other language.
http://sourceforge.net/projects/gnocad/]GnoCAD is a Solid Modeler for Linux. It use OpenCASCADE libraries and Gtk+/GNOME. The purpouse of this project is to give to Linux community a functional and useful CAD system.
Don't know if any of these are good, just checked sourceforge.