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!
Iconscout - Design Resource Marketplace.
Craftwork - A collection of User Interface resources made by Craftwork
clay.css - Micro CSS util class for applying inflated fluffy 3D claymorphism styles to HTML elements.
3dicons - 3dicons library offers beautifully designed open-source 3D icons.