It’s a serpent. Don’t know what it is google “serpent instrument”. This is in my my chain of instrument builds that I hail above almost all my other builds. So far I have made a Bach Stradivarius trumpet, a pocket trumpet and a bugle! And I adore wind instruments (particularly brass) and if you have any ideas for a build JUST TELL ME because the serpent instrument that I am talking about was requested by a user.