Which marble run is best? Marble runs are rolling ball sculptures you build yourself. You assemble tracks in all kinds of wild configurations and watch as the marbles roll down hills, around corners ...

You've probably seen the famous pendulum demonstration—the one where the physics professor puts a bowling ball on a rope, holds it by her head, and lets it go, knowing it won't have enough energy to ...

There are few things that can keep a certain kind of mechanically-inclined mind entranced as well as a marble run, and few structures that look as interestingly organic as procedurally-generated ...