As an umpire, an engineer, an equipment junkie and someone who does some fabrication work with baseball gloves (see link:
The Glove Shop), I find your project fascinating.
I've always wondered about the padding in a chest protector. What about that "memory foam" stuff- do you think that would work? I remember when this product first came out, there was a demonstration on TV where a guy laid a sheet over his hand and invited someone to whack his hand with a hammer, with no ill-effect.