This is a view of the test fitting of the side walls showing the construction detail of the torsion boxes. The instructors in the course were very much in favor of torsion boxes. Basically they are a ladder-like framework sandwiched between plywood sheets. The image shows the framework and outer sheet before the inner sheet is attached. The grey objects are steel brackets that will stabilize the walls and anchor them to the wagon bed.In a traditionally built wagon the walls would have been constructed of one or two large (12") wooden planks, edge joined, and then anchored in the same way, with a series of large C-shaped brackets.
After using the torsion box method which involved having to square up and align, many, many parts, and repeated test fittings and removals from the wagon chassis, I would opt for the traditional method, cut your wood to size and attach it. Ever so much simpler
