[Peter V. Dell'Orto]

I wouldn't bother apply DR to touch spells. If meteoric iron is unaffected by magic, it should just block the spells period, nevermind give some DR. I'd think it would do that now, as written, because presumably the magic is going from the mage through the armor to you (and if not, you're not actually touching the target). The Magic Resistance approach is okay, but I'd probably make it more effective than that, yet more limited - works on spells that affect the body parts covered only, helmets block mind control magics, body armor blocks most whole-body spells unless delivered by touch to another body part, etc.

The cheapest torso armor is 20x cost and thus in the 4K range, and blocks good and bad magic equally well. That's good enough for me, personally.

As for the "tinfoil" approach, just disallow it. Seriously, why make up complex rules instead of just saying, no, you can't usefully make meteoric plating for armor, it needs to be solid, and the thinnest form you can make is light scale or mail?

Just because some munchkin starts blathering about foil plating doesn't mean you have to provide it or let them make it. If you compelled to make them, just make sure you apply very, very harsh rules about rusting, layering armor, damage to armor (foiling will scrape off, and even a small scrape removes the defensive nature of it), etc.