Hi - I don't plan to sell them ... they are easy to do. I of course first bought some extra knobs from Yamaha first, in case I messed things up. That wasn't necessary, but I did it in case I decided to paint some knobs [I may later experiment with painting some knobs white and adding a black "line" just for fun.]

I did this on a table (knobs not on the Genos). I used ¼" vinyl letters (the kind you can buy in most good-sized office supplies stores (or online). I used the capital "I" letter, which is basically a white line ... and put it on the edge of an X-acto knife. I cut it to size (somewhat "by eye"; no measuring) to make a white "line" about the size needed for the knob.

Then using the X-acto knife and a bent-open paper clip, I placed the "line" (part of the letter "I") into place on the knob. It is a bit tricky to get it in the exact right place - but the X-acto knife helps here; moving it around and "tucking it in" (pushing it in a bit) to place. . .

Jim