This morning I found a site full of pretty amazing marble machines, many of which involved a small hand-crank to power them. There were links to other cool ones like this.
It filled me with fond memories of the marble machines scattered across Pinewoods Camp, made by Tom Senior. Some were vertical and some wandered back and forth on various walls. Some bathrooms had them which made for sweet chiming noises coming from small wooden buildings here and there. Sometimes there would be one at auction and it would be cause ferociously bidding until someone won that year’s treasure.