The automotive enamel is the only way to go when rattlecan painting a frame. Even that isn't going to be chip proof but it's as close as it gets.

The only way to get your paintjob to last is in the preparation, i.e. very good prep work. Nice clean surface to paint on, smooth primer coat... smooth sanding... even color coats... let dry for a week minimum since it is an enamel... wet sand... then clear coat... also waiting a week for this clear coat to dry.

It you wait the maximum time that it says on the can for an enamel paint (a week) your paint job will have the best durability possible from a rattle can paint job, and even that isn't much...

I have done a few rattle can jobs, with one that looked almost factory when I got it done. Took me about 3 weeks total from sanding to clear coat... the trick is in how much time you put into it.