Things metal box
Picked up the metal box from the zinc plating works today. They certainly had tried to get it clean. The inside was virtually flawless (only a few spots) but the outside was still as it had been:
Inside Things metal box - almost flawless
Outside of Things metal box - still some work needed here.
I’ve decided to keep this box instead of getting a new one (which had been my plan following the intial disaster). So I’ll have to carefully sand down the outside of the box to remove the spots before installing it into the pinball machine.