Print-in-place whistle (over 110dB)

A loud little safety whistle that prints in one piece and works straight off the bed, with a loop for your keys or a lanyard. Air from the mouthpiece runs through a thin flat slot and splits on a sharp edge over a closed chamber, the same way a referee's pealess whistle sings. Make the chamber bigger for a lower note or smaller for a shriller one, with a pitch estimate as you go, and fine-tune the slot, window and edge if yours is breathy. It prints on its side with no supports.