OpenSCAD - OpenSCAD is a software for creating solid 3D CAD objects.
OpenJSCAD.org - OpenSCAD + JavaScript = OpenJSCAD, edit locally or remote online, preview in browser direct via...
FreeCAD - An open-source parametric 3D modeler
PLaSM - Programming Language of Solid Modeling
CadQuery - CadQuery is a parametric cad script framework
BRL-CAD - BRL-CAD: Open Source Solid Modeling