Lexan popped into my head because its easy to work with. Aluminum works too. Can cut 1/16” with a knife and snap. Just takes a few passes with a sharp blade. Aluminum is soft and can be shaped slightly. Can saw it too. This may give you ideasIt is “double bubble” insulation. Hum didn’t think there would be that much turbulence but for sure I’ll check it. In fact I’ll maybe I’ll buy a piece of lexan your advise has never failed me yet. That glue I used is some tough stuff.
There is a lot of air space above it and below it. But maybe I do need to come up with a better design. I’ve always got to do things around running my business, being with my wife and kids, normal life, and endlessly never having the time to do much for myself!