Blender - Blender is the open source, cross platform suite of tools for 3D creation.
SheepIt Render Farm - A free distributed render farm for Blender
FreeCAD - An open-source parametric 3D modeler
TurboRender - Rendering at your workstation?
Sculptris - Sculptris: Enter a world of digital art without barriers.
SuperRenders Farm - SuperRendersFarm.COM is a CPU & GPU cloud render farm, supporting all 3D Render Engines: Arnold, Redshift, Octane, Vray, and more.