Thomas Network - ThomasNet.
CGTrader - CGTrader is an online marketplace at which artists can sell and buy Revit and 3D models.
Zycus Procure-to-Pay Solution - Zycus' Next Generation Procure-to-Pay Solution acts as a GPS for your P2P process. The P2P solution provides: Easy-to-use: Amazon-like shopping interface & Google-type search engine + Guided buying.
3DExport - 3DExport is a 3D model marketplace where you can buy and sell 3D models, CG textures and digital objects for 3D printing with royalty free. Professional 3D models - 3DExport.com
HALFEN CAD-Libraries - AutoCAD - CAD-Libraries - AutoCAD - Software / CAD - DOWNLOADS
TurboSquid - TurboSquid offers 3D models for professionals.