the local paintstore here does package 2-comp laquer in aerosol cans, but with a friendly gas, apparently.
air-drying stuff often uses water as a base, but it should be bakable. You won't damage the aluminium box, so stick one in a moderately hot oven and see. If it fails you can always sand it off.
I prefer baked enamel and 2-C laquers. Automotive stuff usually is one of the two and should be fine.
see if you can find something intended for boats - that's often very durable.
hih