I had a student who had one last year. i couldn' t make it work, but Brad Harris can make it sound good. You can make a tube call out of a 35mm film cnaister or a prescription pill bottle. cut a half moon out of the bottom and cover most of the opening with a piece of latex (from a glove or balloon, different thicknesses give different sounds). Hold the canister in your thumb and fore finger (like and o.k. sign)with the latex side up, place your lower lip on the latex and say tuck to start. Work on different sounds from there.