I went to assemble the lid and door before I realized, finally, that I can’t both use inside corners on the extrusion the forms them and have captive pieces of polycarbonate in the groove. So now, after cutting all the pieces, I’m pondering how to attach them. Maybe I got the order of operations wrong!
The easiest way is probably the same thing I did with the frame of the Cantilever printer design based on leftovers — for each joint, tap M5 the hole in the extrusion, and drill a corresponding hole for an M5 through the middle of the piece it abuts. There are only two places where I would need two screws to occupy the same place, and there I can use corner plates. 16 holes total I think. And I’m all out of corner plates, so I’ll have to buy or make a few.
Hopefully I have all the screws I need. I’ll see.