415-C Side windows info

I need to replace mine due to them being scratched and dirty etc during the felt replacement process.
Acrylic or Plexiglass? Which one is preferred? Also where can I find the info for the size and thickness etc.
Does anybody like Vern sells them precut or is it up to us to find them in the market?

One last question... The railing where the felt goes is a little wobbly, wavy at some points. Is it possible to make it stretched somehow so it can be evenly straight?