The first concept involves increasingly large bins that empty some material (water? bouncy balls?) from smaller to bigger as time passes. (The top box would be seconds, the bottom hours, and so on.) It could be done with a physics library in Processing but might not be that interesting. I think I’m going to move forward with the next idea instead.
The sketches below are the beginnings of my Monster Clock. (The first page is the primary rumblings, the second page has the more developed concept. For the Monster Clock, little monsters would appears on three different tiers, each of which is hinged at the middle. At the 60 second/60 minute/hour mark, the floor tilts to one side and pours all the monsters into the mouth of a bigger one on the platform below. I may use just boxes that condense into a larger box to start with in case the animation/illustration of the Monsters ends up being outside of the scope of the project given the quick timing.