Whistle
thingiverse
A whistle I designed from scratch some years ago for a dive trip. At the time I used PLA, but I would suggest PETG now.
Download Model from thingiverse
With this file you will be able to print Whistle with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Whistle.