I'm going to suggest using Lexan. And to hold it in place, go to any place where they install windshields. Tell them you want a tube of glass adhesive. Or, if you want clear, they may have that too.
I remember the day I tried to cut tempered glass. All was good until I tried to snap the cut-line.....................then..............KA-POW!!!!!! Glass everywhere
Tempered glass can be cut. As long as the procedure in doing so is done correctly. A laser or a Diamond blade & a wet system to keep it cool. The right glass shop will have the tools and have the ability to cut it for you. Expect to pay more than standard glass cutting prices though.
You can always ship your pattern here--->
Cutting Tempered Glass Patterns