I used Red Heart super saver for this one, because it tends to create a stiffer fabric. I cut pieces of cardboard to place on the inside for each of the four sides and a piece for the bottom so the shape would be closer to a true “box” and not a rounded square. The black bits at the top and the white windows are foam with sticky backs, and I did end up writing “Police Call Box” in each black square around (actually used white nail polish with a fine detail brush, came out great).