Alex when i was imaging i did build a box for my Canon 5D, it was a fair bit of work and it was made out of Copper sheet, quite thin but sturdy.
Mate it is a pain in the arse to get it all to work with the fans/heat sinks and other electrical gadgets needed.
I did get it built, but then to attach the bloody thing to the Camera and Scope, i gave up and sold it off never used, to a member here
But give it a go Alex if you are pretty handy.
Leon