Here is the earliest photo. The sides are up and the cross ribs for the roof are being placed. I'm building in my back yard under a pop-up. The sides are only 5mm underlayment to keep the weight down. Later, battens will be glued to the sides for more strength. After the ribs are in place the sides must be braced 90° to the base/floor. Further construction will stiffen the sides and they need to be straight!