You guys are talking about a kind of Duxochrome thing, eh?
Hexavalent (Ian) has been toying with this idea I think, on the spurring of CMB.
But if hardening is such an issue with polymers, I just fear that none of these schemes will apply well. It makes little sense to set out learning guitar with one hand tied behind your back, or trying to build a car that doesn't use wheels.
Of course finding a way to do it with PVA would be a really great contribution, but gelatin & in turn leather have been utlized for centuries because of its unique property to tan. I'm not sure we should expect a polymer to have any of these same characteristics.