Divider, Shelf, Plate or what you want to name it. Unsure if the physics would allow it but allow these to be crafted as a 1x1 grid map square. Allow them to be placed on a leveled surface which allows dirt to be placed on top of them for a 'second floor' not interfering with the dirt below the plate. 10x10 grid, 10 of these plates. 40 gathered or salvaged metal plates, etc.
For us terraforming fanatics out there.