This is do right up my street..
[youtube]http://www.youtube.com/watch?v=IvUU8joBb1Q[/youtube]
How it works - Part 1:
https://www.youtube.com/watch?v=uog48viZUbM&t=201s
How it works - Part 2:
https://www.youtube.com/watch?v=p0Guq7vZb_E&t=124s
And done with Minecraft:
https://www.youtube.com/watch?v=X__oo9HptN0&t=10s
A new and improved machine is in build, just search " Wintergatan Marble machine X "
Jan