A place to paste good websites where you can download stl files for printing.
Edit: Made this a Wiki-post so everybody can edit and add links! @tjub
Current ones I use are:
Thingiverse - Digital Designs for Physical Objects
A good site with mostly if not all free files
Cults ・ Download for free 3D models for 3D printers (cults3d.com)
This one has some free and some paid for stl files - pretty good quality files
Discover STL files for 3D printing ideas and high-quality 3D printer models. | MyMiniFactory
Mainly paid for stl files but some really top notch stuff on here
More paid for stl’s, nice quality