Report as inappropriate

I used this motor: http://www.amazon.com/gp/product/B00AUCGJX0/ref=oh_aui_detailpage_o08_s01?ie=UTF8&psc=1.

There are many motors of similar format, just select one that runs around 75rpm.

You may want to check out this thing: http://www.thingiverse.com/thing:1852963. It is a smaller but sturdier design, and prints in fewer pieces.

A Mini Merry Marblevator Christmas Tree