The Wizards Spellbook
This box is designed to store your Modular Realms magnetic gaming terrain hidden in a box disguised as a book on your bookshelf!
It has a beautiful glossy finish and is made of a thick sturdy card that enables it to double up as a dice tray when your terrain is in use.
I have 3 of these and they're a great idea for a storage container.
They're solidly built and can take a decent amount of terrain per book. Each of mine holds a complete Dungeon Lord pack, so there's plenty of room.
They're also the right size for fitting on a bookshelf as described, they fit well alongside other books or into a dedicated bookshelf for your TTRPG accessories.