- http://cinema4dmaterials.com/
- http://www.c4dzone.com/en/download/cinema-4d-5/
- https://www.behance.net/gallery/6960933/Free-Cinema-4D-Material-Pack
- http://www.cgmotionbox.com/2013/07/450-free-textures-for-cinema-4d/
So far, I'm unfamiliar with C4D so I don't know if the libraries below work as intended but here are some more that I found:
- http://www.c4dexchange.com/en/default.aspx
- http://8bitfactory.co.uk/?p=300
- http://www.raptor4d.com/
- http://bestm8.deviantart.com/gallery/
- http://walan4ik.deviantart.com/art/Terrain-materials-pack-C4D-258674007
- http://3dericdesign.deviantart.com/art/Free-wood-pack-texture-193590616
- http://3dericdesign.deviantart.com/art/Floor-C4D-free-158195272
- http://3dericdesign.deviantart.com/art/free-floor-pack-1-for-c4d-144781012
- http://smokeyoriginalhd.deviantart.com/gallery/33187445/Materials
- http://ostin.deviantart.com/art/Car-Paint-3-for-Advanced-Render-Physical-401856038
- http://neon-monkey.deviantart.com/gallery/
- http://nobiax.deviantart.com/gallery/ (look for "free texture pack". There were 58 at last count.)
- http://borysses.deviantart.com/gallery/5901662/Textures
- http://still-cg.deviantart.com/art/architecture-material-pack-104780212
- http://2753productions.deviantart.com/art/Cinema-4D-Auto-Shader-Pack-153311580
- http://2753productions.deviantart.com/art/Cinema-4D-Granite-Shader-Pack-157989881
- http://diza-74.deviantart.com/gallery/31577105/Textures
- http://lyotta.deviantart.com/gallery/32621704/Textures
- http://elfabiofx.deviantart.com/art/Cinema-4D-Material-Pack-over-1000-Materials-340328779
- http://martinacecilia.deviantart.com/gallery/6034914/tutorial-and-resources (look for marble textures)
- http://elementsunleashed.deviantart.com/art/C4D-Texture-Pack-1-62347853
- http://www.conzo.ch/download.html
- http://www.motionsquared.net/secret-page/
- http://www.c4dcafe.com/ipb/files/category/27-textures-materials-bump-maps/
