Quite a few years ago I participated in an architectural design class at a local junior college. I designed a way to score a flat sheet of cardboard into a grid of triangles and to fold the grid into a rigid tube. I had an intuition that I could form more complex models, such as a torus, but could not figure out the geometry. 3D printing allows for a more colorful and flexible solution. Many complex and pleasing models can be built from this simple hinged triangle.