pump top (toy)

This drill ( http://www.thingiverse.com/thing:731086 ) reminded me of a pump top I had when I was a kid, so I built one.

Updated: see end note.

Action video (no knob version): https://vid.me/MiuW
And a virtually unedited version with dishwasher noise, smacking it across the kitchen floor: https://vid.me/R6JD

The piece here is printed in ABS and I had some cooling artifacts, but at a 10 hour print rate, I'm going to accept that for now. It uses _a lot_ of plastic because there is some hidden thickness printed at a 90% fill rate on the lower wide part of the top. This weighted ring allows it to keep it's momentum for long spins, and the low center of gravity keeps it fairly stable. You can see this in the cutaway view picture.

**Variations on the screw drive**
There are two versions of the screw drive. One has cylinder at top on which you can glue the knob after assembly. It looks nice, but it adds weight high up and tends to induce wobble. I printed my knob holl