I currently use Tamiya masking tape for masking ho scale trains. The product provides great results. The product is easy to use. It works well at keeping paint from seeping through. The tape also works well with curves.

This 3 mm Tamiya tape, as well as ALL of the other sizes, work great for creating crisp lines to separate one color from another, or to protect areas you do not want paint on. No blead under!

Holds the sharpest line I’ve seen yet, but I haven’t tried automotive tape. This is easier to get a hold of, and possibly cheaper.