This seems a pretty fun one, thought I’d give it a go.
I can’t reveal all of the backstory of my “Ultimate Crate/barrel”, because I’m doing this for a side project with a couple of mates, and I don’t think we want to publically announce the project yet. 
How this Item will work, is you’ll come across one, and once you’ve figured out how to open it, held between the two boards is a piece of parchment with a sigil painted on it, that is a clue to the greater puzzle of the “game”.
Here’s the concept:

Oh yeah, it’s about the size of a large dictionary.
)
Must agree love the concept art, It will look great once textured 