A month or so ago, in a moment of weakness, I bough a double neck Gretsch guitar, only to find out that there was no case available and wasn't going to be.
I found Ken, the owner of a custom shop in california called Blue Heron. He built one off a tracing of the instrument. At a little over $300.00 it wasn't cheap, but of the highest quality...it's GREAT. Plus, he's a great guy and does what he says he will.
If you have a need for a unique carrying case/bag, why not het hold of him? Don't have his web address at hand, but a Google search of Blue Heron bags will get it.
Russ