Logic gates made from pulleys and weights

Alex Gorischek's Pulley Logic Gates is a brilliant and delightful demonstration of attaining a set of logic gates with pulleys, weights and string, using materials you can buy cheaply so you can try it out yourself. Watch this video: the gates build in complexity and ingenuity as they go along, and by XOR, I was actually cheering (and it gets even better than XOR!).

(Via JWZ)