MANY-BELLED KELP HORN
Most lip-buzzed brass instruments use valves or slides to vary the sounding length of the tube and change the sounding pitch. Another option for brass instrument pitch control would be to have several belled tubes of varying length attached to the same mouthpiece, with valves to shift from one to another. This is not unheard of: if you look up schalmei you’ll find (among a few other types that this word can also refer to) some very eye-catching multi-belled brass instruments. Further digging will reveal other types of many-horned horns that have appeared at various times. You can make a multi-horn yourself using valves salvaged from an old trumpet and fitted with several kelphorns of varying lengths. Kelphorns? Yes, the seaweed called bull kelp is plentiful on U.S. west coast ocean beaches. With its hollow, conical shape it can make excellent horns when dried.
Sorry, no audio clip for this instrument, since in old age I’ve lost what little brass chops I ever may have had. Hopefully I can get a brass player to provide an audio clip at some point. Suffice it to say that the sound is very much like a trumpet.