I first saw a wooden Bass Clarinet bell in London in 1976.  Stephen Trier had made it on a lathe in the backyard  of his home in Hammersmith. I was struck by the beautiful craftsmanship, which  allowed one to appreciate the wood's natural grain.

Since finding bell-sized pieces of hardwood is not easy,  there are those who resort gluing two smaller pieces together!  Rossi Bass Clarinet bells are created from a single block of  African Blackwood (Dalbergia  Melanoxylon) from Mozambique . This wood is hard enough to provide the beautiful, deep sound the instrument requires. Players using this bell include
Howard  Klug ( Indiana University ), Henri Bok (Rotterdam Conservatory) , Pedro Rubio ( Madrid Conservatory) and Carlos Escalona
( Simon Bolivar Symphony, Caracas).
VIDEO : Howard Klug playing a piece for bass clarinet by Jorge Montilla: