Loose Thrust-like Bearing

UPDATE: 2 (3 actually) really key bits: Added hex shafts so things can actually turn on it, and added a little snap-y thing so that when closed the balls won't fall out. The snap bit is a little big, I filed it down, but as I only need one I didn't bother tweaking the file.

I needed a thrust bearing type thing for the gyro/pendulum/hamster in my [Lego BB-8](http://LegoBB8.com).

I had bought a small bearing, but decided it wouldn't work, and I have some 1/4" Acetal balls lying around, so