FreeCAD - An open-source parametric 3D modeler
Xmind - Xmind is a brainstorming and mind mapping application.
MakerSCAD - Powerfull 3D design tool for 3D printing, virtual reality and game engine.
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.
OpenSCAD - OpenSCAD is a software for creating solid 3D CAD objects.
Coggle - Coggle is a simple, beautiful, powerful way of structuring information.