How to fix crack in aluminum back cover?

Hi.

I have a bent and cracked aluminium back casing on my Air 2. right next to the lightning port.

I can't find a replacement back casing, and the repair service offered a refurbed one in stead of fixing it (at a higher price than a new one, I might add :( ).

I'm thinking of either superglue or epoxy. Would that work or could it glue something on the inside that should not be glued?