Jaco Pastorius, the man who revolutionized how the bass guitar is played and who is, for many, the best and most influential bass guitarist ever, didn’t start his musical life on the instrument. Instead, the man who would be the master of the fretless electric bass was a drummer!
As he developed as a player, Jaco had experimented with creating fretless basses. In the early 1970s, he acquired a 1962 Fender Jazz bass, which either Jaco acquired already fretless or from which he removed the frets with a butter knife (his recollections varied over the years). Jaco filled in the areas where the frets had been with plastic wood and coated the former fretboard with epoxy. This bass, which was the primary fretless instrument he recorded with, and Jaco nicknamed it the Bass of Doom.
just...BASS! 