Printer's box corners

I was not happy with differential cooling during prints on the side that was closer to the room wall, and decided to build an isolation enclosure for my printer.
The box walls could be anything, but in this particular project I plan to use scavenged styrofoam. However, any other isolating material should also work.
Attached files include mounting corners and joints for such walls.

Future work:
1. I hope to convert it into configurable for the wall width.
2. I suspect, given that some wall are really thin, I might need to enforce it with aluminum tape, to add some sturdiness.

Details: current for that side walls of 10 mm and back wall/support of 20 mm
There is no ceiling or floor at the moment for this enclosure.