I'm thinking you could make a mold and produce them from tough plastic for real cheap.
Plastic molds, even from my guy which is a real low cost, starts around $2,500 and probably $5,000. I asked. Matt said is was not worth it since plywood works so well, and it does.
Plywood also has the nice ability to be user customizable. Hands too small, make the holes closer. Board too small, make a new one larger. Heck, Matt stood at the stern and made a nice custom job in just a few hours. He even used some epoxy ( I *think* is was epoxy), and painted it orange. Nice job, too! Real professional outcome.
They could be made of injection-molded plastic, but basic tooling costs thousands, and I just don’t see a mass-market. Anyway, anybody can make one from plywood.