As mentioned in the first post of this project, I planned to store the hills in an A3 box. I don't have A3 boxes, only A4 sized ones, so I cut off the sides of two A4 boxes and joined them. The bottom MDF sheet is glued into the box to get a strong and sturdy box bottom. For the vertical spacers, I used ePVC as well.
Under the second and third MDF board, I glued strips of doubled-on-themselves packing tape to use as handles to lift the boards out.
