I have two Calton cases, one custom made for my Further and one for my Martin D-28. I bought them more than 10 years ago, when Calton was still in Canada. If they are making them essentially the same way, I believe there are better options. The Calton cases are quite heavy. I have since obtained a Hoffee carbon fiber case. It is supposed to be just as protective as the Caltons, but at far less weight. I don't know if Hoffee will make one long enough for an Alembic bass, but it is worth checking out. I believe there is another company or two out there that is doing carbon fiber cases. I'd look there instead of fiberglass like Calton.
Bill,tgo