You can find attached an assembly instruction in an included pdf.
it is and hybrid beetween a serpent and an ophicleide. an opheicleide shaped serpent or a keyless ophicleide
The ophicleide is a musical instrument that was commonly used in the 19th century, primarily in orchestral and military band music. It is a brass instrument that is essentially a keyed version of the serpent. The serpent is a wind instrument that dates back to the 16th century. It is a type of brass instrument that is made of wood or brass and is shaped like a long, curved tube with a mouthpiece at one end and a large bell at the other.
The author marked this model as their own original creation.