Simple kids toy with handle and fan, where pulling on the wound up string rotates the fan. Once the string stops pulling, the fan lifts and flies off. My kid can easily get the fan to reach the 3rd floor.
The handle and the embedded shaft print in place. Print horizontally with supports. The supports within the gap of the shaft and handle can then be broken off with few turns after printing. Lubricate with lithium grease or oil for best results.
I used a strong, braided nylon string, ~50cm. Threaded and tied off one end through the hole in the shaft, and other got looped for kids to put fingers through.
Handle assembly can be printed in PLA or PETG. I chose to print the fan in TPU, making it a bit safer for my kids. Although any material should work. If you want it to go higher, try making the outer fan ring a bit thicker or some other way to add small weight to the circumference (not a lot, else the thing won't lift up).