Blender - Blender is the open source, cross platform suite of tools for 3D creation.
FreeCAD - An open-source parametric 3D modeler
MATLAB - A high-level language and interactive environment for numerical computation, visualization, and programming
meshmixer - meshmixer is an experimental 3D modeling tool for making 3D mashups without too much hassle.
Inventor - Inventor is a 3D CAD software that lets you quickly create 3D models with embedded intelligence, intuitive workflows, and optimized performance.
Onshape - Onshape is the first full-cloud 3D CAD system. It runs in a web browser and on any mobile device.