FreeCAD - An open-source parametric 3D modeler
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
VARKON - Varkon is a very powerful parametric 2D/3D CAD, modeling and application development tool for...
3D Cityplanner - Urban and real estate development at your fingertips. With the 3D Cityplanner it’s possible to create, visualize, analyze and share 3d plans online.
Vectorworks - Vectorworks 2D / 3D CAD and BIM software for Mac or Windows provides one flexible solution for your entire design process. Sketch, model, and present with the ultimate software from start to finish.
Silo - Silo is a focused 3D modeling application with the ability to effortlessly switch between organically sculpting high-poly models and precisely controlling hard-edged surfaces.