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.
"Tamiya 3 mm Masking tape"
bpd78530 (Bel Air, MD)
This product will work well for masking off cockpit canopies. Tamiya quality at a good price from HobbyLinc.
"Tamiya Masking Tape"
automaticstuff
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!