You will need either an old fidget spinner, or some bearings. The bearings out of my fidget spinner were exactly 22 mm in diameter and 7 mm deep, and I believe these 608ZZ bearings are standard. They're not glued in, just apply pressure and pop them out. They can also be purchased directly, if you want a bunch for a class or something.

You will need access to a 3D printer. The best one I've used for reliability & ease of use is Dremel's Idea Builder.

Micro-centrifuge tubes are inexpensive - a cent or two each when bought in bulk.