OpenSCAD - OpenSCAD is a software for creating solid 3D CAD objects.
FreeCAD - An open-source parametric 3D modeler
OpenJSCAD.org - OpenSCAD + JavaScript = OpenJSCAD, edit locally or remote online, preview in browser direct via...
ImplicitCAD - ImplicitCAD is a programmatic CAD program, implemented in Haskell.
CadQuery - CadQuery is a parametric cad script framework
RapCAD - RapCAD is a Rapid prototyping CAD IDE for RepRap and RepStrap 3D printing machines.