An Object with zero tile-thick walls and a door. The door and container are two tiles wide, and the interior is eight tiles deep. The interior acts like any other interior, and the container can have other objects inside it.
The doors are heavy-duty and often locked.
Containers can be carried by semi trucks, cargo ships, trains, etc.
They are occasionally habitations of the poor. Rural cannibals, dockside thieves, trainyard hobos, Favela Dwellas