BTW, the tray turned out to have been galvanized from the factory
Rustoleum makes a cold galvanizing spray. It comes in very useful when restoring old computers that have got a bit of surface rust on the case. Again, not quite what I'd use externally, but it is a decent match for IBM Personal System/2 cases. To your use, if the galvanizing is indifferent, give this spray a look.
Cold Galvanizing Compound Spray 7785830 - 16 oz. Spray
https://www.rustoleum.com/product-c...galvanizing-compound-spray?ls=7785830&lc=Gray
Holy Snap! Just searched for galvanizing...
https://www.rustoleum.com/search-results/?searchStr=Galvanizing
NOTE: There were two colors, the first a dull sheen, the other, bright. I wondered where the bright sheen one went to:
RECALL: Rust-Oleum Professional Bright Galvanizing Compound Spray 7584838 and batch code H0304A
Hazard: The bottom of the pressurized container can detach unexpectedly, posing an injury hazard.