cavelamb himself wrote:

Another advantage of using the clear plastic is that it is possible to
get AR grade scraps. The AR grade is scratch and UV resistant. I
also found it to be much less brittle that any plexiglass or lexan
I've ever worked with in the past. I was able to cut the 1/8" sheet
very effectively with a pair of sheet metal shears (then I cleaned the
sides up with a belt sander, followed by a 400grit sanding block).


Nice for flat parts, but how does it heat form?


I haven't tried it yet, but it sounds like a "hot project" that I need
to get around to.