Blender - Blender is the open source, cross platform suite of tools for 3D creation.
FreeCAD - An open-source parametric 3D modeler
SketchUp - 3D for Everyone
MATLAB - A high-level language and interactive environment for numerical computation, visualization, and programming
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
Inventor - Inventor is a 3D CAD software that lets you quickly create 3D models with embedded intelligence, intuitive workflows, and optimized performance.