Scott Rickard set out to engineer the ugliest possible piece of music, devoid of repetition, using a mathematical concept known as the Costas Array. In this talk, he shares the math behind musical beauty (and its opposite).
(Filmed at TEDxMIA.)
The Mousinator (prototype). Requires no physical contact from whatever goes inside to activate. Used a ping distance finder to determine how far in the critter is and then slams the door shut to trap it inside.