I came across this list
Stlfinder.com
https://thangs.com/
https://thingiverse.com
https://Cults3d.com
https://sketchfab.com
https://pinshape.com/
http://www.3dshook.com/
https://grabcad.com/
https://www.cgtrader.com/
http://www.turbosquid.com/
https://3dexport.com/
http://www.yeggi.com/
https://www.remix3d.com/
https://fab365.net/
www.tinkercad.com/things
www.cgtrader.com
www.forge.zheng3.com
www.trinpy.com
www.digible.net
www.shapeways.com
www.yobi3d.com
www.youmagine.com
www.3dwarehouse.sketchup.com
www.3dcadbrowser.com
www.123dapp.com/gallery/content/all
www.libre3d.com www.3dshook.com
www.3dexport.com/free-3d-models
www.tf3dm.com
www.treatstock.com/3d-printable-models
www.open3dmodel.com www.archive3d.net
www.3dcontentcentral.com
www.shapetizer.com
Gumroad.com
https://3d-gallery.xyzprinting.com/en-US/promotion
https://3dprint.nih.gov/
https://3dexport.com/
https://repables.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 h
ttps://www.3dagogo.com/
https://www.malix3design.com/?m=1
https://dtrstudio3d.wixsite.com/website
https://www.zsculptors.com