Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Sculptris - Sculptris: Enter a world of digital art without barriers.
meshmixer - meshmixer is an experimental 3D modeling tool for making 3D mashups without too much hassle.
Misfit Model 3D - Misfit Model 3D is a 3D model editor that basically operates with triangle-based models.
Sketchfab - Sketchfab is an industrial design software tool is useful for ideation and for beginners in the industrial design field.
SculptGL - SculptGL is a browser-based 3d-modeling application.