how do they make highlighters?
Off topic:
When I worked in the college bookstore a student came in and asked for a highlighter. I started laying out all our various kinds and colors. “No,” he said, “I need a highlighter.”
While I was still recovering from my “Huh?” he reached over and picked out of the rack… a black magic marker.
So now everytime I see a black magic marker, I call it a <insert group-to-disparage of your choice> highlighter.
/off topic
As to your OP, haven’t a clue. I would guess it takes a special transparent ink. Although we also sold a highlighter that was made like a mechanical drawing lead holder, only the lead was a solid yellow material. It was for marking very thin, fragile pages like in bibles and such.
chief,
What aspect of highlighter fabrication has you baffled?
I think they make highlighters pretty much the same way they make all other markers.