Gentlemen, forgive my abrupt insertion. Perhaps you can try using a hollow Snooker cue stick to make a whistle body. Its material is made by winding carbon cloth, which is stronger than ordinary carbon fiber pipes. Its inner hole is conical, with an inner diameter of approximately 23 centimeters to 10.5 centimeters and a wall thickness of approximately 1.4 millimeters. The length of a single piece is 145 centimeters, and the selling price for a single piece is about 35CYN. A Snooker cue stick can be used to create bodies for low D, G, and high D. You just need to make a whistle head to join.
I’m not a seller of this cue, I just tried using it to make a low D body for my low D whistle, and the effect was pretty good.