Cut a length of river cane down to about 1 foot long. Carve one end flush to one of the divisions inside the cane.
Heat a length of metal rod or coat hanger in a fire, and push it through the cane to remove the nodes between the sections of the cane. Be careful not to remove the one at the opposite end as it is required to make the sound.
Carve six holes using the tip of your knife along one side of the cane. Carve one hole -- the hole you will be blowing into -- about 2 inches from one end, and the other five evenly spaced from the other end, every 1 inch.
Blow across the hole closest to the closed end while blocking the other holes with your fingers.