This is a simple model of a Swiss lever flying tourbillon as found in many high-end watches. A tourbillon is a feature designed by Breguet as a method to counter gravitational errors on the balance spring and improve watch accuracy. This tourbillon, however, was designed by me as a method to demonstrate horological nerdom to others.

vocabulary lesson:
tourbillon - a mechanism to counter the effects of gravity by rotating the escapement and balance wheel so all errors average out.
"flying" - cantilevered off of only one pivot. "Flying" sounds more dramatic and sells more watches than "cantilevered."
swiss lever - the most ubiquitous mechanical watch escapement in the world originally invented by Thomas Mudge. Its simplicity and ability to self start account for its popularity despite less than ideal efficiency and sliding friction from the pallets.

Originally I wanted it to be powered by my ID tags, but it requires more weight (or a bigger spocket). So now it runs off of six quarters taped to the end of my ID tag chain (standard #3 ball chain). It keeps fairly accurate time at 1 RPM, but I left holes in the balance wheel into which one can thread grub screws to adjust the speed.

See it in action: https://www.youtube.com/watch?v=Wy9oI43SeyU&feature=youtu.be

I designed it yesterday evening and printed it this morning, so I may not have caught all errors. It seems to work quite well, but please shoot me a comment should anyone discover any issues while attempting to make one.

I attempted to keep the part count (printed and hardware) as low as possible. In addition to the printed pieces (less than four hours of print time and 32g plastic). This design requires the following (Barbarians that do not stock shafts and ball bearings should consult the update below for an alternative):

3 x 20mm long 2mm shafts
1 x 30mm long 3mm shaft
2 x 6x2.5x3 RC helicopter bearings

Here are links for the non-printed components I used. Anything comparable will do.
bearings: https://www.amazon.com/Sixteen-MR63-3x6x2mm-Precision-Bearings/dp/B01M0VV96I/ref=sr_1_2?ie=UTF8&qid=1483062996&sr=8-2&keywords=3mm+id+ball+bearing
3mm rods: https://www.amazon.com/10Pcs-Stainless-Steel-Cylinder-Linear/dp/B00JR56KI0/ref=sr_1_1?rps=1&ie=UTF8&qid=1483063060&sr=8-1&keywords=3mm+shaft&refinements=p_85%3A2470955011
2mm rods: https://www.amazon.com/20Pcs-Stainless-Steel-Round-150mmx2mm/dp/B00KHUR5AQ/ref=sr_1_1?rps=1&ie=UTF8&qid=1483063100&sr=8-1&keywords=2mm+shaft&refinements=p_85%3A2470955011
inspiration: https://www.bulleit.com/whiskeys/bulleit-rye/

UPDATE 04FEB17: Due to several requests for designs that do not require metal shafts and ball bearings (and also due to the fact that my Dremel is half way across the ocean), I added new versions of parts designed for 1.75 filament shafts. Basically, any file with a "-2" in its name has been re-dimensioned for the thinner, floppier shafts.

To use, straighten spare lengths of filament and thread them through the holes of rotating parts so that about 4mm is sticking out of each end. Sand the ends of the filament lengths so that they are rounded. This version may no longer be called a flying tourbillon on account of the bridge, but the mechanism is identical. It also prints a few minutes faster.

This new version is just as reliable as the previous one although operation is a little rougher. I doubt many of my other designs will be as forgiving of the filament shaft conversion, but who knows? Anyway, I would be interested in hearing about others' experiences with this update and whether it's something worth pursuing in future designs even after I am reunited with my Dremel.

UPDATE JAN18: new PLA spring-powered variant https://www.thingiverse.com/thing:2751917