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GrabCAD Library - The GrabCAD Library offers millions of free CAD designs, CAD files, and 3D models. Join the GrabCAD Community today to gain access and download!
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
Thomas Network - ThomasNet.
TurboSquid - TurboSquid offers 3D models for professionals.
ActCAD - ActCAD is one Software for many applications covering the primary domains of – Architecture, Engineering, Construction (AEC) including Structural, Electrical, and Mechanical.