I was looking at some photos of bandsaw boxes when I noticed that on one,
the joins where the different pieces were re-glued back together, seemed to
have a neat black line between the two pieces. It gave it a nice hi-lite on
the join rather than trying to hide it. How is this done?

I remember seeing something similar on boat decking where there was a black
line between the boards that made up the deck.

Thanks Jaz.