I recently viewed a very entertaining/interesting premium-channel history of the Eagles. In one segment Timothy B. Schmidt was playing a fretless bass guitar that was distinguished from most of the fretless basses I have encountered by having fret "lines" on the surface of the neck but NO actual frets, in addition to the dots presenting themselves to the player on the top side of the neck. It is challenging enough for me to sound "true" bass notes on basses WITH actual frets; and there is a very high-end Brubaker fretless bass available for use with El Sledge (+). Mr. Schmidt appeared to ameliorate the challenge(s) for modestly talented players by having these fret markers on his fretless bass. Do any of the musicians/players out there know of a facility (or luthier) qualified to customize our Brubaker by accurately adding these markers to an existing, already-fretless bass guitar? My intuition is that it would be easier (for me) to negotiate this challenge (and contribute a fretless sound when required) were I to have these metaphorical "training wheels" added to this beautiful instrument.