1 thing i learned is you can really beat 16 gauge sheetmetal.
heres another poorly made non fitting heater hole patch panel.
the mess im working with
fit
notice the extra 1/8 inch of bead
the blue line is how wide it should be.i hammered the hell outa the area on the other side of the blue line to flatten it out so the beads matched
the bottom piece was really no fun
what i ended up with