I'm sure by now everyone has seen the Marble Machine? He calls them marbles, but they look like little pinballs - they certainly get magnetised like pinballs.

Here's the original Marble Machine:

There's a how it works:

He's building a new improved one. There's heaps of little videos in his channel explaining his design and construction.

Making tracks:

There's heaps of other interesting stuff in his channel for MMX CNC, magnets, 3D printed parts (like drums): https://www.youtube.com/user/wintergatan2000/videos