This is a remix of https://www.printables.com/model/495173-flat-pocket-whistle I modified it in tinkercad to cut off some sections to make it smaller. I printed it and it still functions! The image shows a print of one of the options from the remix source. The orange print is this model.
The print settings mentioned on the original are:
no-supports
2mm layer height
perimeter value of 2 (not sure what this one means)
nozzle size of 0.4 mm (probably doesn't matter?)

If you'd like to remix the tinkercad, you can do so here: https://www.tinkercad.com/things/hXBYultWHgh-pocketwhistle?sharecode=jZkp475BZ3Vve2MOmAwp0fcmukVzqCaApJ4iXiglEIk