Tractol is an enamel paint, and traditionally popular amongst tractor owners.
There are quite a few suppliers of enamel paint.

Somewhat topical - https://www.mig-welding.co.uk/forum/...-gloss.110427/
awemawson is someone I know who loves to refurbish machines, and has discussed paint types on at least one of his threads on madmodder if you want to lose an hour or two down that rabbit hole.

For sheet work, I'd either be looking at spraying, or foam roller.