Open Peeps - A hand-drawn illustration library.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Control Illustrations - 108 free flat illustrations with customizable characters
Autodesk 3DS Max - 3ds Max is software for 3D modeling, animation, rendering, and visualization. Create stunning game enrivonments, design visualizations, and virtual reality experiences.
DrawKit - MIT licensed SVG illustrations, in 2 styles
ZBrush - ZBrush is a digital sculpting and painting software solution.