Only polyhedraother than tetrahedron where each face touches all other faces. This one has 7 hexagonal faces. Each faces all the other 6.
1000 years Calendar
Hamilton
Dudeney T Disscetion
Classical Dudeney T Disscetion to Square. We have made this with Eva Sheet and Magnets
Great Stellated Dodecahedron
4D structure.
120 dodecahedron. This is half the 120 cell.
Dodeca
Dodeca
Stomachion
This 14 pieces can be arranged as a square in more than 17000 ways. 2000 yr old game
Straight Line Motion
Rotate the handle and pen draws a straight line. Beautiful mechanism. Smaller pulley is half the bigger. Based on Hypocycloid or on.