I printed @mroek's Cyclone triple track marble machine and loved it. However, being rather lazy I wanted an easier way to operate the marble lift. So I replaced the drive cap with my own that has a Phillips' indentation at the top, thus allowing a Lego Mindstorms motor to drive it with ease.

mroek's Cyclone triple track marble machine:
http://www.thingiverse.com/thing:1340784

* IMPORTANT* Because the original STL for the marble machine was too large to print using my Dreamer, I printed the marble machine at90% scale. Therefore, this cap will ONLY fit a 90% scaled machine! You could try scaling this cap UP to 111% which might then fit the original scaled machine.

Here's my video of it in action:

Print Settings

Printer Brand:

FlashForge

Printer:

No

Supports:

0.2

Notes:

Because the original STL for the marble machine was too large to print using my Dreamer, I printed the marble machine at90% scale. Therefore, this cap will ONLY fit a 90% scaled machine!