Locomotives have used steam train whistles since the early 1800s. A steam whistle is loud enough to signal a train's arrival over great distances; the train engineer pulls a small lever that releases steam into the whistle chamber and emits the sound. You can build a simple model steam whistle with soldering and metal-cutting tools and just a few basic materials that you can find at a hardware or hobby-supply store.
Press down on one end of the 3 1/2-inch-long brass tube with a pair of pliers until it is flattened.
Attach the rotary wheel to your rotary tool and use it to cut a 1/4-by-3/8-inch rectangle into the piece you just flattened to form the whistle's mouth. Flatten the tube above and below the mouth you just cut into it.
Sharpen the whistle mouth's top edge with a small metal file.
Solder the small scrap of flattened brass onto the inside of the whistle mouth, leaving a gap between it and the bottom edge of the mouth.
Attach a small drill bit to your electric drill and drill a small hole on the opposite end of the brass tube, so the hole is between the flattened piece of brass and the end of the whistle, closer to the end of the whistle.
Insert the small brass tube into the hole you just drilled and solder it in place. Blow into your whistle to ensure it works. Adjust the filed end of the whistle mouth if it is not making any sound. After you confirm that the whistle works, solder the other end of it to the steam source.