Matthias writes -

I hadn’t actually planned on building a second marble machine, but in March 2000 I had an idea for building a better marble elevating device, plus I had enough time on my hand to actually build a machine using this principle. And this is the machine I built… What inspired me to play with building a marble machine again was the idea for a marble elevating wheel, which would be very unlikely to jam.

Building Marble Machine 2 – [via] Link.

Related:
Matthias’s Marble machines page – Link.