How to make an Aztec Death Whistle (without clay)

I did something very different here. This is an imitation of an Aztec death whistle, which produces a sound similar to a scream in agony. I basically used 5 things: a piece of 40 mm diameter pipe, a 25 mm PVC cap, an aluminum tube (6 mm internal), a plastic washer and glue. Note that the position of the aluminum tube in relation to the cap is very important. The large hole at the bottom of the tube is exactly to facilitate the positioning of the cap. Larger caps produce more bass screams; smaller caps produce sharper screams.