FreeCAD - An open-source parametric 3D modeler
Justinmind - Define awesome experiences through wireframes & prototypes.
SketchUp - 3D for Everyone
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
avocode - Centralize design collaboration, version control, prototyping, feedback, and developer hand-off with Avocode. Work on any design, anywhere, with anyone. Sign up free 👉 https://avocode.com/.