I've just completed a DIY LED fretboard on a P-Bass, and I documented the process and wrote a short tutorial and video.
It's posted on my website: www.DIYRibbonMic.com/ledfretboard
Disclaimer: This involves removing the fretboard from the neck. I did it on a $40 Squier bass, not an heirloom Fender, but it works! Total cost = $70 (including the bass), and about 10 hours of work.
Inspiration and thanks go to several other internet postings where people did similar projects.
- Rickshaw



