These are the process documentation of the forth prototype.
This method requires thick layering (x3) of the side walls on the main frame structure.
Reason for the layering is to allow adequate slot/space for the flaps of the shell pieces to *lock in.
This method is an effort to reduce the percentage of velcro used and also to hide most of the corrugated sides of the cardboard planes. (cleaner side profile)
More detail-lings can be seen on the photos below.