Blender - Blender is the open source, cross platform suite of tools for 3D creation.
FreeCAD - An open-source parametric 3D modeler
Sculptris - Sculptris: Enter a world of digital art without barriers.
Onshape - Onshape is the first full-cloud 3D CAD system. It runs in a web browser and on any mobile device.
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.