Blender - Blender is the open source, cross platform suite of tools for 3D creation.
KiCad - A Cross Platform and Open Source Electronics Design Automation Suite
SketchUp - 3D for Everyone
LTspice - LTspice® is a high performance SPICE simulation software, schematic capture and waveform viewer with enhancements and models for easing the simulation of analog circuits.
AC3D - AC3D is a 3D software for games, virtual reality and flight simulation, scientific, medical and general data visualisation, rapid prototypes of 3D designs, 3D printing, Google Earth, X-Plane, Second Life and more.
Fritzing - Fritzing is an open-source initiative to support designers, artists, researchers and hobbyists to...