I made a very basic Aztec Death Whistle, stripped down to the bare minimum so that it prints fast and gives a loud sound.

A convenient design to put inside other models to make novelty whistles - see https://www.thingiverse.com/thing:5024825

Blow into hole in the top and it makes a really loud screaming sound. Changing the blowing angle affects the quality of the scream (maybe I will introduce a mouthpiece at the optimum angle) and altering the print size varies the pitch.