Yeah! Iknew stuff like this was out there. Those dancers are awesome. Playing with the gears and cogs from watches made me think a little about how they do it. Those gears are cut by hand sometimes, the precision is mind boggling. Magnification is, obviously, key and I think tool rests are a big part of it plus some knowledge of math...
losing interest...
Here is some 'freehand' on the head of a pin and Pinhead: