This instructable shows how to make a telescoping whistle from brass cases. For this, you will need:
1 .223 Remington/ 5.56mm NATO/ 5.56x45mm spent case
1 .30-06 Springfield/ 7.62x63mm Spent Case
Twist Type Pipe Cutters
Step 1: Prepping the Cases
Take the pipe cutters and cut the .30-06 Springfield/ 7.62x63mm case and cut to a length of 1 9/16 of an inch/ 4 centimeters, so you should have a straight brass tube with the base of the case at one end. Leave the .223 Remington/ 5.56mm NATO/ 5.56x45mm case alone, however, insert case base first into the cut down .30-06/ 7.62x63 case. The case should be swallowed up to just below the shoulder.
Step 2: Crimping the Case
Insert the .223/ 5.56mm NATO/ 5.56x45mm case into the cut down .30-06/ 7.62x63mm case. If you left it there from the last step, that is OK too. Take the pipe cutters and tighten them just so the cut down .30-06/ 7.62x63mm case is indented. Do this all the way around. The other case should not be able to slide out. Pull the .223/5.56mm NATO/ 5.56x45mm case up to this mark. Indent the cut down case again, however, do it lighter and slightly below the base of the inside case this time. It should just close around the base of the .223/ 5.56mm NATO/ 5.56x45mm case, however, the .223 case should be, with pressure, able to slide back down. When pulled up, it should lock between the crimps.
Step 3: Using the Whistle
Blow on the end of the raised .223 case. With a little angle adjustment, it should make a whistle.