Wait, if the strings are inside the bass where do you pluck?
you don't, you just hit the instrument against the floor
my idea: picture a fretless bass, but with an array of miniature LED's under a clear fingerboard. you could program this array to show where the frets would be for alternative tunings, whether you're talking about other equal temperaments or just intonation schemes. perhaps its not such a useful idea for the average bassist, but it would be a great educational tool.

