I made a case for my 500c, and I used a sheet of perforated metal from amazon that I cut with my angle grinder and then spray painted. You could even cut this stuff with some good shears if you are willing to take some time to do some measuring.
Yeah, for my very first 800c. A little lighter gauge than the original but still OK. After that, like bb, I started making my own out of a sheet of perforated metal where you can make 4-6 for around the same price.