Children and some adults love whistles, especially ones that sound like train horns. You can make your own train whistle from a short, notched section of PVC pipe and two wooden dowel pieces. The project requires only basic sawing and sanding skills. A word of caution, however: This whistle is very loud and really sounds like a train whistle.
Cut a V-shaped notch 5/8 of an inch from one end of the PVC pipe. One side of the notch should be perpendicular to the pipe and cut into it half way. The other side of the V-shaped notch should be at a 45-degree angle to the first one. In other words, the first cut is straight down into the pipe and the other cut is slanted in to meet the first one. Sand the notch slightly so that there are no burrs or rough edges.
Test one of the wooden dowel pieces to see if it fits inside the PVC pipe. It should fit very tightly so that when it is in position it will not move. If it does not fit inside the pipe, sand it around one end of the circular outside until it just starts to fit into the pipe. This way you will be able to tap it the rest of the way in with a hammer.
Remove the dowel piece from the PVC pipe and cut or sand a flat side onto it. The wood removed on the flat side should be about 1/8 inch at the peak of its curve. Therefore, the width of this dowel from the flat side to the opposite curved side will be 3/8 inch.
Tap the wooden dowel piece into the end of the PVC pipe on the notched end. Line up the leading end of the wooden dowel piece with the vertical cut of the V-shaped notch. You will have to first use the hammer to start it and then use the length of 3/8-inch wooden dowel as a punch tool to continue tapping the flattened dowel piece into the pipe after the end becomes flush with the pipe's end.
Tap the other half-inch wooden dowel piece into the other end of the PVC pipe to seal it. You may have to sand it to get it to fit into the pipe, just like the other piece. Once it is inside the PVC and seals it securely and does not move, you do not need to continue tapping it in. At that point you can just cut off any excess that is protruding from the PVC pipe so that the dowel is even with the end of the pipe. Sand the whistle to remove any burrs or rough spots.