I tried the Testers paint pen for doing lugs and i like the results.You can trim the tip to the thickness you want with an exacto knife.

Nice job. I just bought a paint pen to do the lugs on my Miyata, which is being painted at the local body shop. I've got a few old junkers around to practice on first.

Very nice looking Schwinn vincev.

Here is an early 80's Azuki Gran Sport that I changed the coloring from brown to black. I used a paint pen and trimmed the tip as well. My advice would be take your time, work with a fine tip and try to keep the lines flowing smoothly around the lugs.