Baccala

probably glass reinforced nylon or nylon 12 if I had to make a first guess. considering its likely to take puck impacts 3d printing might not be the best route. I think your best bet would just entail cutting your own. maybe chop up the shell of an old shin guard or see if you can get a manufactured sheet of nylon reinforced polymer (like the stuff they use for magpul stocks or g19 frames.) easiest option would certainly be some thick leather/synthetic leather. Any cobbler should be able to do it, but they just won't be rigid pieces like the original 55flex product you were looking for.

I cant really get a good picture, but has anybody noticed that makar has a liner in his re-akt helmet shell that looks shockingly close to a CCM nest tech/3d printed liner? if you see him on the bench, look closely at the vents on his helmet. it appears to be blue to match the shell.