This instructable will teach you how to make an incredibly simple and cheap PVC pipe slide whistle that works pretty effectively.

Step 1: What You'll Need

This PVC instrument is pretty easy to make and requires few materials. Here's what is needed:

A PVC pipe, at least 12" long. The great thing about this instrument is you can use any length and diameter of PVC that you want. For this we used a 12" PVC pipe with a 3/4" diameter
A wooden dowel, that is a few inches longer than your PVC pipe. Try to get a dowel that matches the diameter of your PVC pipe so that the clearest sound is produced, we didn't have 3/4" dowels so we used a 1/2" one instead.
A ruler
PVC pipe cutters
A hot glue gun (not pictured)
A hand saw
A coping saw
A vise grip (not pictured)

Step 2: Cutting Your PVC Pipe

Now you'll cut the hole that will actually generate sound.

Take your PVC pipe cutters, and chose an end to cut a hole in
Its up to you how far from the end you cut the hole, and it can vary depending on the length of the pipe, but for this one we made the first cut 1 and 1/2" from the end
Make the first cut vertical and go about halfway down the pipe
Then make a second cut about an inch away from the first cut, this one at an angle so that it forms a curved triangle shape

You want to position this hole close to the end of the pipe so you will be able to generate as many notes as possible

Step 3: Making the Stopper

This stopper will be cut from the wood dowel and will go in the same end that you cut the hole in. This is where you will blow air in to the instrument to generate sound.

Cut a segment of the wood dowel off, this segment should be as long as from the end to where you made the first cut for the hole in the last step, so for us this segment was 1 and 1/2" long.
Very carefully cut about 40% of the dowel off using the coping saw so you have what resembles a semi-circle (as seen in the picture)
Use the hot glue gun to glue the stopper in with the flat end facing towards the hole you cut