How to make a swiss wabler bird calling whistle?

Question

I have seen these things before and decided to order one off of ebay. They seem like pretty simple instruments so does anyone have any ideas of how to make one myself and what materials I could use as I cannot find any instructions on google. Thanks

Answer 1

Take the two end caps from USED shot gun cartridges, knock out the percussion caps and join the caps together with a loose fitting rivet through the centre hole, flat side to flat side. Place in mouth, on tongue,  and . . . well this is the bit I can't get right., blow through them to make them vibrate.