I would recommend with out hesitation the Mazda two part touch up paint. I bought mine from MX5 Parts.
I had a real nasty chip on the wheel arch. The touch up process was carried out over 2-3 days. I used four coats of the base paint followed by two coats of top coat.
The result was outstanding. Pictures in sequence below.
The result is only effective once the top coat was applied. I felt I was getting nowhere until this went on.
I followed the instructions to the letter. Including the very very light rubbing over the repair with the damp gauze (all in the instructions).
I did not rush this job and was astounded with the result.
Oh yes, there were tears 
Three base coats. 
Getting there now 
Wow, wow, wow, you have to be close to see it 