Re-model of a whistle seen at Prusa site, added hook so it can be used as a keychain. Optimized for 0.4mm nozzle. Print it with 2 walls and 3 layers top/bot. Infil not needed.

Added stp, and ipt file so you can modify it and some text etc.

27/06/2019 Edit: Added Keychain whistle v2 with 0.8mm sides. To be printed with 4 top/bottom layers.