List of sites that offer free stl files

TinyArtist

https://thingiverse.com

https://Cults3d.com
https://sketchfab.com
https://pinshape.com/
http://www.3dshook.com
https://www.printables.com
https://grabcad.com/
https://www.cgtrader.com/
http://www.turbosquid.com/

TinyArtist

https://3dexport.com/
http://www.yeggi.com/
https://fab365.net/
www.tinkercad.com/things
www.stlfinder.com
www.shapeways.com
www.yobi3d.com
www.youmagine.com
www.3dwarehouse.sketchup.com

TinyArtist

www.3dcadbrowser.com
www.123dapp.com/gallery/content/all
www.libre3d.com
www.3dshook.com
www.3dexport.com/free-3d-models
www.tf3dm.com

TinyArtist

www.treatstock.com/3d-printable-models
www.open3dmodel.com
www.archive3d.net
www.3dcontentcentral.com
www.shapetizer.com
Gumroad.com
https://www.stlfinder.com/
https://3d-gallery.xyzprinting.com/en-US/promotion
https://3dprint.nih.gov/

TinyArtist

https://3dexport.com/
https://repables.com/
https://www.instructables.com/
https://libre3d.com/
https://3dkitbash.com/
http://www.rinkak-services.com/en/
https://library.zortrax.com/
https://fab365.net/
https://polar3d.com/
https://free3d.com/
https://www.threeding.com/mobile
https://nasa3d.arc.nasa.gov/models
http://zheng3.com/forge/index.php?id=-4
https://www.redpah.com/
https://digilab.dremel.com/resources/lesson-plans
https://www.3dagogo.com/
https://all3dp.com/

TinyArtist

https://3dorchard.com/
https://www.malix3design.com/?m=1
https://dtrstudio3d.wixsite.com/website
https://b2b.partcommunity.com/community/partcloud/
https://www.zsculptors.com
https://crealitycloud.com/

TinyArtist

https://freedees.com/
Cookie Caster - http://www.cookiecaster.com/
Lithophane - http://3dp.rocks/lithophane/
Instructables - http://instructables.com/
NASA 3D Resources - https://nasa3d.arc.nasa.gov/