We have scoured the web for some of the best repositories of free 3D Models. Below is a current list of a number of sources and websites that offer free 3D Models.

1. 123D                                     
2. 3DaGoGo                             
3. 3D Cola                                
4. 3DM3                                    
5. 3DModelFree                     
6. NIH 3D Print Exchange    
7. 3D File Market              
8. 3DShook                              
9. Archive 3D                          
10. Artist-3D                             
11. Bld3r                                   
12. CadNav                                
13. cgtrader                              
14. Cults                                    
15. The FORGE                         
16. GrabCAD                             
17. MorphoSource                   
18. Nasa 3D Resources         
19. Pinshape                             
20. Repables                       
21. Rascomras                         
22. SketchFab                     
23. Sweet Home 3D               
24. Shapeking                     
25. STL Finder                          
26. Smithsonian X 3D            
27. Thingiverse                    
28. TF3DM                                 
29. Threeding                           
30. TurboSquid                       
31. Treasure Island                 
32. YouMagine            
33. Veggi                  
34. Yobi 3D   

Autodesk repository
Designs have been tested that they are printable
Some free, some paid 3D models
Model bank
Mostly architectural models
NIH 3D Print Exchange for publicly available biomedical files
Most popular designs have been verified that they are printable
Free trial, Over 1600 models $10 for 12, $25 for 40 models
Mainly architectural 3D Models
3DS Max Models
Printing social network, models are from various sites
Free 3D models, and textures
3D Models and Low Poly 3D Models
Many fun objects
Free 3D Printed Models
GradCAD Community CAD library
Very large repository of fossils and bone 3d models
Official NASA 3D models (for spacecraft and space objects)
Community to share or sell designs
3D printable file repository
3D model platform in Spanish
3D Models
Architectural
Exchange of 3D Models
.stl search engine
Smithsonian 3D Printing
Community for discovering, making, and sharing 3D printed things
Download 3D Models
Marketplace for free and paid 3D printable models and files
3D Models for Professionals
Printable with FDM.
Where makers collaborate on 3D designs
Main 3d model search engine
3D Search Engine