Mimic Ink

Wondrous item, uncommon

This fountain of ink was made through alchemy using a mimic's blood, allowing its shapechanging magic to be influenced by writing.

When found, there are 1d6 + 4 uses of ink remaining in the fountain. You can spend 1 minute writing a detailed description of an object on a nonmagical piece of paper, expending a use of the ink; the paper then transforms into the object described. If the paper was in a book, the entire book transforms instead (provided it wasn't magical). Regardless of the written description, the object can be no larger than Tiny, and its weight, AC, hit point maximum, and other details are unchanged by the transformation; the object otherwise functions as it should. Describing a magical object does not impart those effects on the transformed object, nor can a transformed object be used as a material component for a spell. If you don't know the exact appearance or shape of an object you describe, the ink does its best to make reasonable assumptions. For example, if you describe a set of keys for the local treasury, the ink will create a set of keys that look appropriate, but wouldn't actually open it (unless you're exceptionally lucky).

Physical interaction with the object can immediately reveal it to be forgery, because its weight is likely different. A creature that uses its action to examine the object can determine that it is a forgery with a successful DC 13 Intelligence (Investigation) check. The transformation lasts for 24 hours or until the object is destroyed, at which point the object reverts to its original form, albeit tattered and damaged.

It's amazing what imagination can do.
It's terrifying what it can do with magic and alchemy.