I couldn't find a case that I liked, so I build one.
It's build with high quality plywood and wrapped with Marshall Tolex.
I build an interface with color coding connectors for easy setup on a 4CM or whatever you need. I also have Variax and USB plugins for the interface so you never have to reach the back of the Helix again.
I have a lot of extra materials, so if you're interested I can build one for you. Just PM me. (this is not a cheap case, BTW)