I haven't used the Nubar Pens Maddie but at a bored moment I did do my toenails red with a black/glitter french style tip using a Spangles Glitter Striper & that worked quite well. I'm still in the very experimental stages with my nail art :lol:
they do have a striping brush at one end, but i find it a bit thicker and stiffer than some ive tried. the spotting end is first rate though, its very fine and controlable, good for fine details and even writing. they do sell empty ones , about 95p i think. the colours are the same as their airbrush paint range so i think that might be whats in them. it would have to be quite thin to come out through the very fine nozzle. i think they are gonna be at n.e.c next month.