[dominicgs]

There is one by Arthur Ganson in the MIT museum[1]. It's part of a great exhibit of fun/quirky machines and there's an interesting video about it on youtube[2].

[1] https://www.youtube.com/watch?v=5q-BH-tvxEg [2] https://www.youtube.com/watch?v=2Rov_Lriqvk