Acrylic is not dirt cheap.
Lexan is pretty darned expensive, especially considering that when you buy a piece as big as a FFH grill, there's a lot of waste.
Which is more cost-effective in the end?
Which is easier to cut and drill?
I've found a plastic fabricating company near my home, and I'm in the process of finding what they'll charge to cut out a cover using a paper template I'll supply them. I'll post this information here, but if it's too dear, I'll probably attempt to make an acrylic one myself. The trouble is that it's so difficult to work with that stuff without it cracking. I kind of dread trying it.