[3.5] Shrink item on worn armor? A cage?

[Caeldrim]

So, what happens if you cast shrink item on something that contains a person or part of a person?

It says specifically in the SRD that you cannot use enlarge person to crush a person, but shrink item has no mention of such stuff.

Does the helmet shrink until it no longer fits on their head and then pop harmlessly off the top?

Does it crush their skull, or just split open to make room for their head?

Would they get a reflex save to pull off the helmet before it crushes them?

What about a creature in a cage, then you cast on the cage?

What about a suit of plate mail? The straps break and the armor just falls harmlessly to the ground?

This seems like a very nasty way to kill someone without any of that brutish swordplay.

[MCerberus]

Generally when you try to use a spell to crush someone or push up against a living being, the spell fails, so I would rule it as such... except the Bigby's fist spells, but those are designed to crush/block/grapple.

Coming with a list, but it's late so my examples will be lame and slow. Wall of Stone forbids you conjuring it in someone for example.


Edit - or using enlarge person as a reference, you can make the items shrink until they are uncomfortably small but not crushing someone. Not many DMs will let you get away with it. It seems similar to someone trying to drown people by using conjure water when someone is talking and getting water in their lungs.