This is a potentially handy little whistle that you can make from an aluminum soda pop can. It really works and sounds like a legit whistle!
Click below for the step-by-step instructions!
First, you will need two strips from the can, one long and one short. These are about an inch wide, the longest is maybe 4 inches long, the shorter about 2 inches. It's not an exact science really, so guesstimate.
Next, you bend the long piece into a question mark/hook type shape. The short piece folds over the end. Make sure to leave a little tab on the longer piece. The short piece will become the mouthpiece for the whistle, the long piece serves as the body.
Here you can see the mouthpiece sandwiched over the end, with the tab ready to fold under. Make sure that the mouthpiece wraps all the way around the longer piece.
And fold that tab under. Almost done here!
Here's a front view of the mouthpiece. You will probably need to enlarge the mouthpiece so that you can blow through it. That's it for construction!
Getting the whistle to actually work takes a bit of trial and error. This is about how you want to hold it--basically think of it as a normal whistle, but with your thumb and fingers forming the sides. You'll need to adjust the curve of the body and the angle of the mouthpiece a bit until you get it right. The first time is the trickiest.
Anyways, a good use of a common found/scavenged resource, and can be made with nothing more than a pocket knife or a pair of sharp scissors. It's actually a surprisingly good whistle, too--pretty loud--and certainly carries further and requires less effort than a shout for help. I think Bushcraft Guru Mors Kochanski came up with this originally, or is at least most often cited as teaching it. Enjoy!