Enderlook
I think I like the first one. Not sure where the Google Form link is, though.
Though I had an idea for the 3x4 sized super-storage: have it full of 'crates' with either the Cannon Shells or the Batteries stamped on them, each crate representing, say, five or so batteries. It's a massive structure, but holds a massive amount of ammo/batteries, represented by the crates.