Slackers unite! After trying to learn to play it as is, I came to the humbling conclusion that, although my single voice lines were improving, I wasn't going to be intonating chords passably on an unlined six string fretless any time soon. I like markers. I need markers. Still, the beauty of the unlined instrument (and the $ignificant co$t of having someone put in subtle ebony markers in the rosewood), led me to search for a way to create temporary lines on the neck. Ideally they would not be visible to anyone but the player, and they would not scar the gorgeous instrument (thanks, Grateful!). Tall order. It turned out there are countless bad ideas in the Home Depot and OfficeMax Ether. Mercifully, most of them are reversible. But here's one solution that's working out so far. Why the neck itself? Bass strings don't stretch or rotate to any significant degree once they settle in. Indelible feltpen marks on the player side of the strings don't get rubbed off quickly, fingerease doesn't dissolve them, and they are only visible from the side, so to the player the neck looks one way (=crutch) , and to the audience it looks the other way (=cool) . Tada! The details are self-evident. A tuner is a decent way to locate the nodes, while a thick paper template protects the neck and provides position reference during inking (and periodic re-inking) . Have your cake and eat it too!