ive used duplicolor products,
i repainted my rims to match the GM red, from there faded pink color,
i also repainted my stock spoiler cause it was faded while the rest of my car is still bright GM red and in near perfect condition,
both the rims and the spoiler match perfectly,
i used a touch up product, i think the 2 in one your talking about, on the area right behind my door, some jerk slamed my car with thier door,
i didnt compound it flat with the rest of the paint yet, so light hits it differntly and it apears a slightly darker shade of red,
ive got a detailing manual that explains how to do such a scratch repair that hasnt steered me wrong yet if you want me to find it and type up what it says about scratch repair i can
i havent seen any product that you could fill up yourself, but couldnt you use a similar small little brush with paint from your body shop for the same effect