This photo shows the basic design of the middle scenic module. The end plates are plain radiata pine and the cross beams are U-channels made up from two lengths of aluminium angle and a thin piece of ply. I used 4mm 3 ply rather than mdf because it is lighter and stronger. The holes were pre-drilled. The cross beams are glued with constrction adhesive and then pop riveted. The cross beams are attached to the long aluminium side beams by more pop rivets.