I call this a circus whistle because it is large and has a bead for a warble sound. Click the play button below to hear the sound. The whistle sounds pretty good once you get the top piece adjusted correctly. You will possibly need to angle it a bit until you get the best sound before you glue it in place.
What child does not like a whistle. Grandpa, the best part is you can send it home with the kids so they and make beautiful music for their parents. :)
For a little more fun, buy some craft paint and let the kids decorate their whistle. Just tape off the mouthpiece before they start painting.
As you can see the pattern could not be simpler. The bottom cut is a stack of two 1/8" pieces. The top two parts are 1/2" thick.
The little round piece in the center of the whistle is optional but give the sound a warble that is cool. Just make sure it is not too small and falls out the soundhole. Don't use a heavy wood or it won't move well.
You can see in the picture above that I have the glue ready to stick on the top wall of the whistle. Notice how the top of the mouthpiece is angled. I moved this piece until I got the best sound then glued it in place. While the glue is still wet you can move this piece if needed.