I built a hand-cranked automata out of LEGO. It looks like 2 frogs racing (kind of… Squint real hard and you’ll see it). The crank is made out of a wheel and operates a cam which moves one of the arms up and down. The arm in turn moves the “frog”. In order to get the other cam and arm moving, there is a system of gears that transmits rotational power along a shaft. The video shows it in action as well as some close up shots.