STLFinder - The 3d models search engine.
Thingiverse - Thingiverse.com is the place to share digital designs for fabricating real, physical objects.
GrabCAD - Helping mechanical engineers build great products faster
Cults 3D - Cults is a marketplace that connects designers and people who want to 3D print some objects.
MyMiniFactory - MyMiniFactory is the world’s leading curated platform for 3D printable objects.
Thangs3D - Thangs3D is an online community for engineers and visual designers that provides unlimited downloads of 3D models and CAD designs.