Ink/Stitch: an Inkscape extension for machine embroidery design
Free and open source pattern design software
Software for electromagnetic simulation
Open Source Planar Linkage Mechanism Simulation and Synthesis Software
OpenNum lets you distribute solvers with a nice graphical interface
Open Knowledge on engineering development.
This plugin exports G-Code for a wirecutter
An Open source Analysis and SImulation Toolbox for Fuel Cells
Open Source FabLab Project
dedalo is a 2d cad drawing software written in python3.