Blender - Blender is the open source, cross platform suite of tools for 3D creation.
SketchUp - 3D for Everyone
FreeCAD - An open-source parametric 3D modeler
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
MATLAB - A high-level language and interactive environment for numerical computation, visualization, and programming
DraftSight - Discover Dassault Systèmes®' DRAFTSIGHT™ Professional CAD software that lets you create, edit, view and markup any kind of 2D drawing. Learn more here.