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.
Sketchfab - Sketchfab is an industrial design software tool is useful for ideation and for beginners in the industrial design field.
SketchUp - 3D for Everyone
ShapeShop - ShapeShop is an advanced and professional 3D design and modeling application that comes with an easy-to-use and user-friendly interface.