Primed all the parts I had prepped and then started the fun part of riveting it all together:
Not shown is part prep for priming and priming. Same old same old. Deburr, round edges, slightly chamfer holes, acid etch and scrub, dry and then prime!
Riveting these corner pieces that end up securing the corner skins later.
These doublers get riveted together with 3/32 universal head rivets which are smaller than the normal 1/8" ones.
Then these doublers are riveted in. The top gets squeezed and the sides get pulled. The bottom gets left open.