On a recent trail run a couple people got separated from the group. Nobody was lost for long and we ended the run with some laughs and jokes about needing survival whistles... which is actually a good idea. Since our club is called the BATS I remixed this whistle with the club logo to make complimentary Bat-Whistles!
Minor filing (or just poking around with a paper clip) may be needed to clear out the airway of any stray filament for a clean sound.
Opened our club logo SVG in Inkscape. Selected the "bat" shape. Used the Paths to OpenSCAD extension to export the path to an extruded polygon. Edited the OpenSCAD file directly to import and superimpose the whistle model.