Hello thank you for quick answer, SkJl47 - the diagram was a draft, the picture that illustrate the most the skeleton is the second, we removed 3 panels and doubled both extremity, All the frame is Plywood and sprayed up with urethane to prevent from humidity to attack the frame. Yes Full plywood panel at the back and doors front and side, but all the doors will open the only part that add strength is the back plywood panel, All the skeleton is plywood (kind of high density plywood) the fiberwood you saw was just a test everything is replace by solid walnut trim and doors. Every part of plywood skeleton are glued together and we used stainless screws.
I will post more picture of the final composition soon.