Shapefest - A massive library of 3D shapes for everything!
Icons8 - Free app for Mac & Windows already containing 39,800 icons. Allows to search and import icons…
LostGeometry.xyz - Huge set of 91 abstract 3D objects in various styles.
Iconscout - Design Resource Marketplace.
Craftwork - A collection of User Interface resources made by Craftwork
Screenspace - ScreenSpace empowers app companies to showcase their products with the power of 3D device videos.