Steam sirens, also known as steam whistles, help alert people before a train or boat arrives. This enables you to move your car or body out of a train's path to avoid danger. However, if you know how to cut metal, you can also make a steam engine to use on a miniature train.
Smooth out the tiny part close to the end of the brass tube using pliers. Cut a 1/4 inch by 3/8 inch rectangular-shaped hole in the smoothed-out location with your cutting wheel to act as your steam siren's mouth.
Fold your siren mouth's side near to the long part of the siren so that it goes into the hole. Smooth out the outer portion of the lip until it appears sharp.
Put the tiny piece of flat brass in your mouth's opening. Then, align it with the side portion of the siren that lies on the other side of the mouth. Allow for a tiny space to exist between the non-sharp mouth edge and the piece of brass. Solder your brass piece to the inner part of the siren.
Turn the siren upside down. Insert a small opening with your drill on the other side of the mouth that sits in the middle of the brass piece and the outer part of the siren.
Put the tiny tube of brass on top of the opening you just drilled and solder it in until it fits securely. Solder the opposite side of your piece of brass to the source of steam.