Paul,
Just search for some of Fred Cesquims building threads. L
]
thanks for the comment Lauri.
Paul, i have been doing that for a few decades, and tried several types of pen and paints. so far the best result is the good old draft pen with india ink ( i mix my own grey color as they shows better over white or dark backgrounds, better grip to the monokote and constant line thickness. Unfortunately they will start to wipe off whith handling or cleaning ( even with a damp water cloth) as the adhesion to monoke is not so strong. I have teste the old top flite pen, results are not so good and if something other than water hit it, will start to smear.
if you want a good lasting result, spray a thin clear coat and you will benefit of having the ink lines lasting forever and the monokote will not peel and will prevent colors from fading due to the UV clear coat resistance. it´s just a few grams of weight added but a striking looking plane that will last longer.
both models here have hybrid finish with monokote, painted trim colors and ink lines, clear coated (wings & tail, fuselages are fully painted). One e-power other is glow.
hope it works for you