Shapefest - A massive library of 3D shapes for everything!
Craftwork - A collection of User Interface resources made by Craftwork
Icons8 - Free app for Mac & Windows already containing 39,800 icons. Allows to search and import icons…
Sketchfab - Sketchfab is an industrial design software tool is useful for ideation and for beginners in the industrial design field.
Iconscout - Design Resource Marketplace.
3dicons - 3dicons library offers beautifully designed open-source 3D icons.