Well, I love that 3d printing thing..
This was a little toy for my son I designed this morning.
There's still something to work on but it already flies.

suggestions are welcome :-)

Have edited the rotor a little. Now it has a deeper hole for the pulley. I hope it won't fall down anymore..

print the files, the grip has do be printed twice.
you will also need some thread/cord and glue.

thread the cord through the hole in te pulley, knot it together. Then put it in one grip half and glue them both together.

now coil the thread counterclockwise, put a rotor on the top of the grip and pull the thread.
you may want to give it a soft push upwards to make it fly better..