a parametric 3D CAD modeler
DXF2GCODE: converting 2D dxf drawings to CNC machine compatible G-Code
Software for electromagnetic simulation
Free and open source pattern design software
LibrePLM integrates CAD editors in Odoo / LibrERP
OpenNum lets you distribute solvers with a nice graphical interface
An Open source Analysis and SImulation Toolbox for Fuel Cells