Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
FreeCAD - An open-source parametric 3D modeler
Invision - Prototyping and collaboration for design teams
meshmixer - meshmixer is an experimental 3D modeling tool for making 3D mashups without too much hassle.
Sketch - Professional digital design for Mac.