[erre]

This reminds me of "Machine with Concrete", by Arthur Ganson: https://www.youtube.com/watch?v=5q-BH-tvxEg

From the video description:

  Each worm/worm gear pair reduces the speed of the motor by 
  1/50th. Since there are 12 pairs of gears, the final speed 
  reduction is calculated by (1/50)12. The implications are 
  quite large. With the motor turning around 200 revolutions 
  per minute, it will take well over two trillion years before 
  the final gear makes but one turn. Given the truth of this 
  situation, it is possible to do anything at all with the 
  final gear, even embed it in concrete.

[ewindisch]

Franklin Institute in Philadelphia has a similar gear reduction setup attached to a hand crank on one side and a metal trash can within a vice on the other side. Children (and adults) are invited to crank the handle and turn the gears. It takes months to crush each can which is then replaced.

[rrauenza]

You can see it at the Exploratorium in San Francisco.