FreeCAD

Overview
Copied from SourceForge:

"FreeCAD is a general purpose feature-based, parametric 3D modeler for CAD, MCAD, CAx, CAE and PLM, aimed directly at mechanical engineering and product design but also fits a wider range of uses in engineering, such as architecture or other engineering specialties. It is 100% Open Source and extremely modular, allowing for very advanced extension and customization.

FreeCAD is based on OpenCasCade, a powerful geometry kernel, features an Open Inventor-compliant 3D scene representation model provided by the Coin 3D library, and a broad Python API. The interface is built with Qt. FreeCAD runs exactly the same way on Windows, Mac OSX and Linux platforms."



Downloading
FreeCAD is available from: https://freecadweb.org/downloads.php.

Installation and configuration
Installation Video

Using FreeCAD

 * Making a Pillow Block Bearing tutorial
 * 3D Printering: Making A Thing In FreeCAD, Part I