FreeCAD - An open-source parametric 3D modeler
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
MakerSCAD - Powerfull 3D design tool for 3D printing, virtual reality and game engine.
DynaMaker - Cloud service for Visual Product Configuration with parametric geometry and CAD / BIM
SketchUp - 3D for Everyone
OpenSCAD - OpenSCAD is a software for creating solid 3D CAD objects.