-PVC with a wide (about 6") mouth and a secondary pipe coming off at an upward 45 degree angle.
-PVC tube that fits in the 45 degree angle pipe.
-1 large black balloon (you might want a few extra in case one breaks)
-table salt or fine sand
1. Cut the top off of the balloon (the long end).
2. Stretch it over the larger opening on top (careful, I snapped a few before it worked for me).
3. Put a large rubber band around it to make sure it stays in place.
4. Pour salt on top of the balloon.
5. Put the PVC tube into the secondary 45 degree pipe.
6. Sing into the tube and watch the salt make formations. It works best if you hold out single notes so the salt has time to react. If you sing a song at a regular pace, the salt will just dance all over and not make very cool patterns. The higher the pitch, the more complex the design is.
7. Have fun!