Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Sculptris - Sculptris: Enter a world of digital art without barriers.
SelfCAD - SelfCAD is an online 3D modeling and slicing software.
ZBrush - ZBrush is a digital sculpting and painting software solution.
SketchUp - 3D for Everyone
Sketchfab - Sketchfab is an industrial design software tool is useful for ideation and for beginners in the industrial design field.