Hello everyone, I'm new to the forum, but as an ex Ordnance Surveyor, 20 odd years of using bow pens and fixed gauge pens every day, I agree that successful lines requires practice. Also a bowpen tuned up to suit the medium(paint or ink etc)and your personal grip on the pen.
As an N gauge modeller,lining vehicles is not impossible, but also not easy! Other uses for a pen can be drawing window glazing bars, and wagon lettering (if you don't look too closely!) Alan.