Rubber Band Copter, available as kit card and as individual parts.

Easy to print and easy to assemble.

No additional components required except:
- a robust rubber band,
- a drop of oil.

How to print:
Line width 0.4 mm, layer height 0.16 mm, first layer height 0.2 mm, no supports, don't print too fast.

Assembly:
Please follow these building instructions, you can find the corresponding pictures above.

1. Break out all individual parts from the kit card and remove any remaining fasteners (pictures 1 and 2).
2. Put the axle into the round bearing plate and insert the rubber band (picture 3).
3. Insert one half of the handle into the round bearing plate (picture 4).
4. Add the second half of the handle, making sure that the two loops of the rubber band wrap around the arms of the second handle part (picture 5).
5. Pull the two loops of the handle evenly over the second handle part (picture 6).
6. Add a drop of oil to the contact surface between the bearing plate and the axle (picture 7).
7. Put the rotor on, the orientation doesn't matter (picture 8).

Do not leave out the oil, otherwise the system will lose too much energy due to friction!

Select a decent Rubber Band!
Not every cheap rubber band will work satisfactorily. I recommend a band that is at least 1 mm thick, 3 to 5 mm wide and 45 to 75 mm in diameter. It should be well elastic and have a decent restoring force. With a good rubber band, 5 to 10 turns of the rotor should be enough to get it to rise a few meters. 
If you only have thin, simple rubber bands, try using 2 or 3 of them at a time.

How to use:
Place the rotor on top and turn it clockwise a few times. Then block it with your thumb until you want it to start. (See short video above).

WARNING: CHOKING HAZARD - Small parts, not for children under 3 yrs!