As I didn't want to do some big works today, I decided to get all the parts needed to fabricate the seat backs. They are only some aluminium sheet getting reinforced by some angle and installed in the cabin with some hinges allowing to move the seats back and forth (three positions) and to recline the seat into two positions. I just got all the parts in the workshop, cut the angles and hinges to length and marked the parts that still have to be cut.