Thingiverse - https://www.thingiverse.com/
Makerworld - https://makerworld.com/
Printables - https://www.printables.com/
Cults - https://cults3d.com/
CG Trader - https://www.cgtrader.com/3d-print-models
Sketchfab - https://sketchfab.com/store/3d-models/stl
3D Export - https://3dexport.com/
MyMiniFactory - https://www.myminifactory.com/
Holy Grail - https://github.com/ad-si/awesome-3d-printing
Thangs - https://thangs.com/
Yeggi - https://www.yeggi.com/
FAB365 - https://fab365.net/
Gambody - https://www.gambody.com/
All3DP News - https://all3dp.com/
TCT Magazine - https://www.tctmagazine.com/topics/3D-printing-news/
3DPrint.com - https://3dprint.com/
NASA 3D Models - https://nasa3d.arc.nasa.gov/models/printable
SubReddit - / 3dprinting