Summary: The important thing is to set the 2 Piano hinges Stangenscharniere exactly between the squares on the pitch and to sink the hinges into the thin wood To do this I bought a Router The first 2 foldable stadiums were made of 6 5mm Multiplex wood Unfortunately the MPX wood tends to twist so I tried the 3rd one with 8mm poplar Pappel
Image Dimensions: 506 x 600
Image originally found here.