We are big quadrocopter fans ever since the XUFO RTF. We really have to re-acivate our TT Copters :-)
Anyway, this one utilizes the axis from the yard-stick earring. Tried to use the smaller diameters of the typewriter axis but it was too fragile, even this one breaks easily when cleaning. Perhaps increasing the diameter or rounding the holder parts would be good improvements.
My next models will most likely utilize push.through rods with a tight fit (and will stick once the model is painted). Printing things fully assembled is a nice way to show off the 3D priner's capabilities, but it's too much of a hassle to do it all the time (at least without dual head & soluble material).
I also had to made the propellors a little fat, but it's a good compromize between not-breaking and not looking too-ugly :-) Or perhaps the worst-case combination of both.
Mirror two opposite props for a more realistic propeller setup... NERD :-)
Daily earrings prologue http://thingiverse.com/thing:7120
Print flat on an UP, or perhaps try "standing"...