When you put a shrunken item in a confined space and the unshrink it, what happens?
Does it work like "Enlarge Person"?
If insufficient room is available for the desired growth, the creature attains the maximum possible size and may make a Strength check (using its increased Strength) to burst any enclosures in the process. If it fails, it is constrained without harm by the materials enclosing it— the spell cannot be used to crush a creature by increasing its size.
In which case, how do you define the item's strength and if it can break its confines? Otherwise, does it break the confines simply because it does not fit in there, provided it is of sufficient hardness?
For example, how does a shrunken cube of adamantine, lodged in the keyhole of a wooden door, behave when unshrunk? Does the door break? Does the cube break? Does the cube unshrink until it meets resistance? Any related rules would be a really nice addition to your answer.
The thing is, I find it more than logical that a shrunken item - especially a hard, dense one - when unshrinking, should be able to break stuff, and not get confined per the enlarge person spell. A hardness check is my best guess, but what happens when I, for example stuff said shrunken cube down a person's throat? Or when I unshrink a previously shrunken ballista bolt, lodged inside a guys sternum?