Okay, Really confused by all of this!
Books are ... big-ish. Too big for most pockets (especially the BIG OL' BOOKS they had back pre-printing press and pre-paperbacks).
What is the purpose of this item?
So .... here's an idea.
Make it a book with a number of pages.
Each page can contain an item.
When you open to that page, you can "pull" the item off that page.
From "2D" to full-size, real life.
As an added bonus, maybe when it's found, it already has some illustrations (aka, items that are pre-loaded).