4" (100mm) x 1" (25mm) square blank.
2" (50mm) x 1" (25mm)square blank.
5/8" (16mm) Forstner bit.
Drill a 2" (50mm) deep hole in one end of the 4" blank using the 16mm Forstner bit. Use either a drill press or Jacobs chuck. Using any bit of scrap wood lying around make a tapered plug to fit the 16mm hole.
This will be used to mount the Whistle blank between centres. Using a roughing gouge turn the blank to 22mm diameter. Shape the bottom 1-2" into whatever you want. Rub down through the grits from 120 to 400 From the hole end of the whistle make 2 pencil marks at 19mm and 32mm.
On the 19mm pencil mark saw at 90 degrees until you feel you are through the wall. (approx. 7-8mm) On the 32mm pencil mark saw at approximately 45 degrees in order to meet the other saw cuts. This is the shape you should be left with. Sand away the saw marks. Now put the 2" blank between centres and turn it down to 16mm or to fit snugly into the whistle hole. When turned flatten one side by about 2mm.
Glue the plug into the hole so that the end of the plug is in line with the 90 degree saw cut. The flattened edge of the plug should face the front of the whistle. When the glue has set saw off any protruding plug. Shape the mouthpiece either on a bandsaw or on the curved edge of a belt sander. Whistles can be made any length but remember the deeper the hole the lower the sound. If you are artistic then decorating could be fun. Make sure that whatever finish you use it is safe to be put in the mouth. Many oils are made from nut.