Powder is difficult to just perform "touch up" I attempted many times when I owned my own coating shop. You can get close with enamels and lacquers but you have to be very careful because they will soften the powder coat even when cured. Its a delicate procedure for sure.
Just say NO to thin oils and M1! 05 F350 Powerstroke 05 Hyundai Tucson 08 Legacy GT