Transparent labels
I decided what size I wanted, wnat color, what font then printed it on adhesive backed peel off clear labels on 8 1/2" X 11" sheets manufactured by Avery Label (and others I'm sure). Print them, cut them, apply them to the panel and cover them with clear satin finish polyurethane. I covered my panel with wood grain formica and the poly brushed only on the labels doesn't show at all. It came out very well, the marking is very durable and I've had no problem updating to accommodate panel changes. Your results on different panel surfaces may (probably will) differ.
Bob Axsom