My advice would be to cut a whole new window. That would leave you a nice big space for an etch. I have the thermaltake tsunami case and that's what I did on it. If you are interested in an etch then we could definitely figure something out.
Your best bet would be to measure the dimensions of the viewable area, as well as the entire plexi, and then when you measure the height you could measure it at the shortest point to the bottom so I know where I can etch. I don't usually cut any special shapes out, I usually just cut it square, so if you had a way to cut the curves at the top and drill the holes then your all set.
It looks like a nice case, but it would be even better with a sweet etch! :P