MeshLab - System for processing and editing 3D triangular meshes, provides a set of tools for editing...
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
noesis - Rich Whitehouse's project web site.
MilkShape 3D - The MilkShape 3D website has been down for almost one week.
SEA3D - An open-source format and tools for game developers 🎮 http://sunag.github.io/sea3d/
Onshape - Onshape is the first full-cloud 3D CAD system. It runs in a web browser and on any mobile device.