OpenSCAD model of a wooden train whistle. This is based fairly closely to a two barrel wooden whistle. I have not printed this so I don't know if it works yet.
The OpenSCAD file contains two settings to change the number of barrels you would like (1, 2 or 4) and internal hole length variance
Print, hopefully make train sounds. chugga chugga CHOO CHOO
I would suggest a 10-20% infill setting, however that hasn't been tested.