There is a VAST array of materials and supplies out there.
The best way is for you to goggle search the stuff you are looking for.
Try searching on "sign supplies" or "Laminated plastic sheets" ---- "romark" (is a brand name for laminated plastics).
You "might" be able to find supplies in www.McMaster.com
As you start to see some of the stuff that suits your fancy - remember the terminology - then refine your searches on the terminology.
THEN - look for local sources.