Printing:

No supports needed except maybe for the pin gear and propeller. I personally didn't use supports and it came out fine. Print the gears and the rack at 100% infill for maximum strength. Enable ironing for that smooth finish. See image for layout guide.

Easy Assembly: 

Place the big gear in 1st, then the middle gear, and then the pin gear in last. Cover with lid and place the propeller on the pin gear. 100% 3d-printed (no screws).

How to use:

Simply hold the rack and firmly pull in the direction of the arrow. 

Enjoy ;)

I'll make a bigger propeller if enough people think it is worth it. I kept it small for now.