The propeller design that Leonardo Da Vinci abandoned; he gave up and decided to invent the glider instead of the aeroplane. You should have seen the wooden V8 engine it was originally attached to.

Schroedinger's Cat: Wanted Dead And/Or Alive, Chocolate, XL

A one-legged stool for people supervising a machine mixing explosives - it's upside down. They sit on it and balance it on the rounded single leg. If they fall asleep, they fall off and wake up.

Schroedinger's Cat: Wanted Dead And/Or Alive, Chocolate, XL