Print in Place Pull Copter

There are a few pull copters rings around now.
This one is print in place, which means, you don't have to assemble the gearbox (The other parts have to be separate, obviously). Just use a pair of pliers after printing to carefully loosen the gear, as it has a few small supports built into the model.

It is all about the speed at which you pull so don't get nervous when it doesn't immediately work. Clearly the cleaner your print the better it will work (so 0.1 layers are recommended)

It is recommended to use TPU for the propeller, less damage and the propeller will last longer. Seems to help also that TPU is slightly heavier.

There is a shorter and a longer key. Both work fine. Again length does not matter as much as speed. The longer one is a little more convenient, but also a little more difficult to print.

Clearly the connection between gearbox and propeller is a bit primitive here but hey, it works : - )

For the gear and key https://www.thingiverse.com/thing:5505 by 3