I have had a few people mention to me about using fountain pens as highlighters. Really? Yup. Take a wide-nib pen like a Pelikan Script 2.0 and use a light yellow ink like J. Herbin Bouton d'Or or Noodler's Firefly, and there you go. A highlighter fountain pen.
What do I think of this? I've heard of stranger things, sure. I really don't see a 'necessity' to use fountain pens as highlighters, but I can see if you're a fountain pen 'purist' and want to use nothing else, sure! Why not?
I won't disclose who, but I've actually been told in confidence that a couple of ink companies that are considering coming out with 'highlighter' inks. I want to know, what do you think? Hot or not?