Fits snugly on a ¾" PVC pipe and should make a clearly audible high pitched whistle when the rocket gets up to speed on the way up.

Like the original there is room inside the body to push 3/8" ball bearings into to adjust the weight 

I printed it using PLA , but it should work with most filaments, and launched it on a rocket using a D12 motor. It whistled quite nicely on the way up despite the fact that it was probably 1000+ feet away.