This is a whistle that I designed based on a whistle cross-section. I've printed it and it does work. Beware, the smaller you print it, the more ear piercing of a sound it makes, and if it's printed too big, it probably won't work. Hope that you enjoy!
(P.S. If you are a Youtuber and would like me to check out their channel, I will gladly do so. Shout out to Make Anything, The3DPrintingNerd, MakersMuse, and RCLifeOn)