DWGFREE - DWGFREE is an online platform that comes with a comprehensive collection of CAD blocks that can be downloaded without the need for registration.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
CADMAPPER - Instant CAD files for any location on earth
Sculptris - Sculptris: Enter a world of digital art without barriers.
MAPACAD - MAPACAD is an online website that is providing leverage to designers and architectures to have the ability to download CAD map cities that can be directly used in their projects.
Misfit Model 3D - Misfit Model 3D is a 3D model editor that basically operates with triangle-based models.