It's built like a brick, but I guess it works. If you were going that route, I might start with something like a Pelican case. They make some in about the right size/shape:
http://www.pelican.com/us/en/products-t … ptop-case/
Other options I've thought about are baking pans, jerrycans, ammo cans, sheet metal + metal brake, and now I'm onto milling out of a solid brick of metal. I suspect you could make a decent case with some hardwood, glue, a handheld router, and some create guiding/clamping. The thermals might be a pain (would need a fan + vents), but it would probably look really pretty.
Oh, and making a foam model then covering it in carbon fiber. I decided that any rework on carbon fiber would be hazardous (dust) and rough on my tools, so I scrapped that idea. Well, that and the layup being more of an art form than I am an artist.
It's really whatever you can dream up and have the time/skills/resources to make, though. I like aluminum because it's a nice balance of cheap, easy to work with, light, and stiff. You can see my design so far here:
https://www.kosagi.com/forums/viewtopic … 2867#p2867
If you want to go the building-a-case route, I'd post in the thread linked above instead of hijacking this one further. Either way, I'd love to see the result!