That's goofy.

JoKe: If you're going that route, why not simply SPOILER ALERT. Click here to see text.

Can you fit small chests inside small chests?

I think a regeneration effect that acted as a multiplier for natural HP recovery would be the most reasonable approach. That way, characters would see scaling benefits as their HP increases.

I feel that giving it a very small chance to effect more substantial healing might be OK as well - something like a 1/50 chance per turn of healing a scar, 1/75 to heal a burn by one step, 1/150 to regrow a lost limb (at 1 HP of course). The chances of these effects ought to be quite small however.

A question worth asking is how powerful such regeneration would be. Not in terms only of how quickly you recover HP, but also in terms of things like - can you heal scars? Burns? What about regrowing limbs?

Item idea: Axe of the Berserker. Functionally a (battle?) axe made of exotic materials. I'm thinking primary material is ruby, secondary is octiron, or ebony. No passive buffs, cannot be cloned.
What sets it apart is a proc, firing with perhaps 1/10-1/12 chance, which grants haste and some sort of regeneration for a dozen or so turns. Powerful if you can keep landing hits, but loses effectiveness when you aren't fighting.

I actually was just testing this. The lightest wishable materials (GEF and grass) have a density of 100, which reduces a 3000g small chest to a mere 500g. Unfortunately, large chests are obscenely large. Even made of grass, a large chest still ends up with a weight comparable to plate armor. However if you have a glut of SoCM, turning a normal-sized chest into grass (because GEF takes a lot of int, and grass doesn't) will still give you a lot of well-protected storage at a reasonable weight of 2500g.

Use a bigger chest. Or a lockbox. If I find a lockbox, I tend to put anything and everything fragile that I really don't want to have breaking/burning inside. Things like scrolls waiting to be cloned, wands of fireball, holy hand grenades, etc...

Bigger chests also provide more protection than small ones. If for any reason you are carrying around more than 6 small chests, you might as well dump them for a medium-sized one. More storage, more protection, same weight. Still, at that point, you're carrying 15kg around, of just chest, not even counting whats inside, so there's that...

If you're carrying around enough chests to where it would be more efficient to put everything in a large chest, you maybe should get rid of some stuff.

EDIT: I seem to be having trouble doing things today.

Not sure you can mine the crystal formations with lightning.

Good point chao