What happens to individual items when you cast a permanent shrink item on a group of items?
Shrink Item can be found in the Player's Handbook page 279:
Shrink Item Transmutation Level: Sor/Wiz 3 Components: V, S Casting
Time: 1 standard action Range: Touch Target: One touched object of up
to 2 cu. ft./level Duration: One day/level; see text Saving Throw:
Will negates (object) Spell Resistance: Yes (object)You are able to shrink one nonmagical item (if it is within the size
limit) to 1/16 of its normal size in each dimension (to about 1/4,000
the original volume and mass). This change effectively reduces the
object’s size by four categories (for instance, from Large to
Diminutive). Optionally, you can also change its now shrunken
composition to a cloth like one. Objects changed by a shrink item
spell can be returned to normal composition and size merely by tossing
them onto any solid surface or by a word of command from the original
caster. Even a burning fire and its fuel can be shrunk by this spell.
Restoring the shrunken object to its normal size and composition ends
the spell. Shrink item can be made permanent with a permanency spell,
in which case the affected object can be shrunk and expanded an
indefinite number of times, but only by the original caster.
The spell can explicitly be used on a group of objects as the description uses a burning fire and its fuel. So there shouldn't be any issue casting it on a chest full of stuff. But what happens if you make that casting permanent?
I doubt you'd get a bunch of objects, each with their own permanent shrink item spell on them… would you? If not, what happens when you remove an item from the chest then try to activate the spell? Does everything in the chest shrink but the removed object doesn't? Will the spell only activate if all the items are present?
Best Answer
The spell requires you to toss a single item
The spell itself does not say what happens if you take the object apart, but the intent of the spell is to treat its target as a single object.
One ruling could be to end the spell when you take the object apart, as if you tossed the object, sidestepping the entire issue. However, in general, spells only check the legality of a target when they are cast, not later. So taking the item apart would not end the spell.
Casting permanency or not has no bearing on the question what happens if you toss only part of the item. It only influcences if you can then shrink again what you tossed without re-expending the spell. Wether you toss the bulk of the item (say, the chest minus one coin, the fire minus one log), or a smaller component (one coin, one log) also does not matter. The question merely is if you need to toss the entire item, and have it revert, or if you can do so piecewise.
While the spell talks about "objects" being tossed, it otherwise explicitly refers to a single object. My reading is that it talks about objects transformed by castings of the spell in general in that sentence.
Tossing will only reconstitue the shrunken object, and and that object is made up from all of its components. Thus tossing will not have any effect if they are not present, because you then are not tossing the shrunken object, only part of it.
If you allowed tossing components to expand them, not only would you get the effect multiple times for one normal casting, it also would mean that the object could be partially in shrunk and partially in normal state at the same time, which is against the intent of treating it as a single object. I think requiring all parts to be present for tossing to work makes the most sense. This would have the side effect, that you could make the object immune form reconstitution through tossing by others, when removing part of it.