If anyone is looking for better pricing on Starboard (or Seaboard which is
very very similar), consider ebay. We buy quite a bit of it here for various
small projects: https://www.ebay.com/str/norvaplasticsinc
You may find some cutoffs that are very close to the dimensions you need for
I recently got 6 small sheets from them. They were discounted cutoffs from
one of their larger production jobs and were in perfect condition with
plastic protective covering. $5 each for 1/2" thick 14"x20" plus
You'd need 7/8" or 1" I suspect.