IRONCAD COMPOSE™ is a valuable tool for communicating 3D design concepts. The download is free to everyone; from designers wishing to share their designs to a sales person presenting their products at the point of sale. Everyone in your team can read data from any CAD system, interrogate the geometry, add their commentary, configure new assemblies, and create real-time renderings and animations.
IRONCAD COMPOSE is more than just a free viewer, it is a revolutionary new way to communicate and develop concepts. It allows everyone to leverage 3D content from anywhere; including company parts catalogs, content suppliers and even general 3D web content. IRONCAD COMPOSE lets you manipulate models and assemblies in real-time which can dramatically reduce your time-to-market.
Downloads MatterControl is a free, Open Source app that lets you organize and manage your 3D prints. It's designed to help you get the most out of your 3D printer - making it easy to track, preview, and print your 3D parts. http://www.mattercontrol.com/
Repetier 3D Print Software http://www.repetier.com/download/
Smoothie Control Board http://smoothieware.org/3d-printer-guide
Docs of Interest i've discovered
Free eBook from GrabCad
Not 3D related But Cool