Larian Studios Forums Divinity: Original Sin 2 Divinity - Original Sin 2 - Game Master Add text to a book, or paper, or tombstone, or ..?

Your best bet is the editor. Create a blank level for all your custom items and update that when needed.
You'll need to get the items as GM and place them as required.

Books are easy.
http://docs.larian.game/Creating_a_book_with_TEXT_inside