Your best bet would be to buy a sheet of lexan. Take some paper to make templates of the shapes with and transfer that over to the lexan. You can then cut the lexan out and install them in the game. It's easiest to cut with scroll saw but I've cut some with a jigsaw and dremel before.

You can paint the underside of them to make them different colors if you'd like or even tape artwork to them if you find something you like. That's really going to be the easiest way to accomplish what you need.

I bought a large sheet of PETG that's about 1/16" thick. It is clear, but I use scroll saw to cut, drill for the holes and sand the edges smooth. If you can find images online print off on whatever translucent material you think would work, apply 3M 467MP adhesive to the artwork side of the print and attach to the plastic.

Check out TAP Plastics. There are a couple locations in San Jose. Tap Plastics provides cut to order acrylic, Lexan and other plastics and at least at the store here in Lynnwood, WA, they have a scrap bin that they sell by the pound. For $3-$5 you can get more than enough to do all the plastics. My recommendation would be 1/8" Lexan (Polycarbonate). I make my own protectors as well as new plastics with water slide decals (Only make them for myself, sorry). The plastics can be rough cut with a band saw, scroll saw a Dremel or even a hack saw, then finished on either belt sander or with a Dremel with sanding drums. If you sand the edges with finer and finer sandpaper you can ultimately polish them to be perfectly clear.

You probably tried this, but did you ask Steve Young at PBR if he had any?
A miracle is always possible.

Yves