Parametric Balloon Nozzle

Simple, quick and easy to print, parametric (you can change the sizes) - this is a nozzle to go in the mouth of a balloon. When you inflate the balloon and let it go, the nozzle controls the rate at which air is released from the balloon, which you can then adjust for maximum flight time, or altitude, or just for fun.

The .scad design includes fins, and I printed a few with fins, but they're not practical at all when it comes to filling the balloon with air, and I didn't see any improved fli