Mirror Sheet corners

Wanted to utilize these great mirror sheets I had laying around to create a curing box for my resin prints.

Here are the sheets: https://www.amazon.com/gp/product/B07JLGR9FJ/
I know those are unavailable, but there seems to be plenty of alternatives. My example pics still have the coating on all but one sheet, but these are great.

These corners give me the flexibility to use whatever size sheets I need.

Printed with supports in the corner and the horizontal groove. YMMV