Sites listed here are gathered from websites that focus on 3D Printing or from Makersmiths user feedback.  Some sites contain free downloads or tools, some are paid.

If you have a favorite site not listed here, please post in the #3DPrinting Slack channel.

Facebook Groups

GroupDescription
3D Printing DealsA place to find deals related to 3D Printing (printers/filament/resin/accessories/etc...).
3D Printing StlsA place to sell, buy and share anything related with 3D Printing, Printers, Prints, Stls.

Model Sources

SiteTypeFree/Paid#Models#Visitors
ThingiverseRepositoryFree★★★★★★★★★
GrabCADRepositoryFree★★★★★★★★
SketchfabRepositoryFree★★★★★
CGTraderMarketplaceFree, Paid★★★★★★
MyMiniFactoryMarketplaceFree★★★★★★
YeggiSearch EngineFree, Paidn/a★★★
Free3DRepositoryFree, Paid★★★★★
PinshapeMarketplaceFree, Paid★★★★★★
XYZprinting 3D GalleryMarketplaceFree, Paid★★★★★★
Dremel Lesson PlansRepositoryFree★★★★★
YouMagineRepositoryFree★★★★★★
Cults3DMarketplaceFree, Paid★★★★
3DExportMarketplaceFree, Paid★★★★★
Zortrax LibraryRepositoryFree★★★★
STLFinderSearch EngineFree, Paidn/a★★
3DKitBashMarketplaceFree, Paid★★★★
ThreedingMarketplaceFree, Paid★★★★
RepablesRepositoryFree★★★
Libre3DRepositoryFree★★
Fab365MarketplaceFree, Paid★★
RedpahMarketplaceFree, Paid★★★
3D WarehouseRepositoryFree★★★★★
NASARepositoryFree★★★★★
NIH 3D Print ExchangeRepositoryFree★★★★★★★★★
InstructablesRepositoryFree★★★★★★★
Ameede.netRepositoryFree

Turbo SquidRepositoryPaid


STL Creation Sites


SitePurposeComments
It's LithoCreate your custom lithophanes.You can upload your own images, select parameters, and create your own custom lithophanes.  Site will generate an STL file for you
LithophaneMaker.comCreate your custom lithophanes.You can upload your own images, select parameters, and create your own custom lithophanes.  Site will generate an STL file for you