A friend once told me that to cover nicks in a car paint job you should apply the standard touch-up paint, but use a tooth pick to do it. That way the paint goes only on the exposed metal and the original paint is untouched. If the "painter" is really skillful, the paint can fill the cavity where the original paint was, leaving a smooth and level surface when it dries.
Suppose this could be done using auto paint in a HA color?
Paul