Flames of War: A Wargaming Blog releases paper terrain retro shipping crates.
From their site:
Dirty, abandoned shipping containers litter the post-apocalyptic wasteland. Some are gathered into barricades, others have been assembled into secure communities. Some have been left in maze like piles, full of long expired sugary drinks on the wharfs of those long forgotten cities… Same size and shape as our original shipping containers so will work well with them, or on their own. Available now on our Products Page.