[dtengineering]

I'd note the "non-articulated" term used to describe the frame perimeter. "Articulated: having two or more sections connected by a flexible joint" pretty much describes those end pieces of sheet metal. I know others have mentioned them as weak, floppy and unwise from a practical viewpoint, but in my take on it, I would also include them as "illegal" as they are articulated due to the flexible nature of the corner joint.

Anyway, sounds like you are on top of it... good idea to post here and ask for advice.

Jason