a parametric 3D CAD modeler
Simple Road Design and Earthworks
3D/2D Concrete Reinforcement in Bentley MicroStation
Open-Source Multiphysics FEA (FEM) Package
Demonstrates a quadtree for spatial indexing of triangles
Design your own pottery for 3D printing in full color
ALST is a CAD for all imaginable logic systems (binary, ternary, etc)
Open Source CAD