Icons8 - Free app for Mac & Windows already containing 39,800 icons. Allows to search and import icons…
Shapefest - A massive library of 3D shapes for everything!
Craftwork - A collection of User Interface resources made by Craftwork
LostGeometry.xyz - Huge set of 91 abstract 3D objects in various styles.
Iconscout - Design Resource Marketplace.
3dicons - 3dicons library offers beautifully designed open-source 3D icons.