@dwizum It's a bit of an undertaking and honestly, I don't even know if I'm doing it right. But I'm glad to share the process and can go into more detail if needed.
- Start with a slotted fingerboard blank, cut to the proper shape of the neck and with the fret slots as shallow as they need to be for the frets.
- The LEDs I use are the "fairy light" style, battery operated ones that are pretty cheap. I got a set for about $5, it was a 30 LED strand. The thinner the wires, the better.
They ran on 2x AA batteries, but I switched the holder to a 2x 2032 lithium for more power and less space.
- I didn't do it this way but should have: do a "false" side of the fingerboard. In other words, add some space for the epoxy to sag. Take a piece of 1/8" scrap or something, then mount it to the side of the board. Plot the side holes and drill them through the false face, into the FB. Go in about 3/8 - 1/2".
Clean the holes out as best you can.
Mix up epoxy and whatever tint material you want (I did white milk paint).
Fill the holes and let it cure.
Remove the false side and trim the side dots to flush.
- Drill the face dot holes next. Use some kind of translucent dots to plug the holes, as evenly deep as you can, then seal those with a little bit of super glue. You don't want epoxy leaking out when you fill all of this in.
- When you have all of the "dots" ready to go, flip over to the back of the board and plot a path for a shallow channel to run all of the wires through. Just keep in mind that you need to make all of the wiring go in a path that starts and ends where you need it. For example, I needed the power wires to come out of the base of the neck, so I started at the 24th fret side dot, went down the neck, then ran it back down to the face dots and finished it just below the 24th set.
- I ended up milling a 1/8" wide channel for the side dots with about a 3/16" gap between the edge of the board and opening of the channel. It was shallow the whole way, but I deepened it in the areas just below the side dots.
If you mark the bit on a table, you can basically deepen it and go carefully and subtly side to side to cut a flat face under the side dots.
If you screw up and cut into a fret slot (like I did twice), fill that with something that you can cut out later, after it's all been filled (mine was styrene, only held in with a dot of CA in the back).
- For the face dots, you can cut another channel shallow enough to make it all the way down the neck. This was something I did by hand, as it wasn't as vital for the light transmission as through the side.
It helps to give some extra room for wiring near any "close to each other" dots because you'd gonna have to tuck wires.
- Once you have a path properly cut, figure out how many LEDs you need. Trim the strand to that number. Most of these fairy lights can be cut off just past an LED and they still work just fine. I think they are parallel wired, but whatever it is, it's pretty cool that they can do that.
- As I said, I started at the 24th dot and I ended up using a hot glue gun to place the LEDs where they needed to be. Super glue was useless for me, but if I had the fancy CA "instant cure" spray, it would have worked.
However, hot glue was easy! I could dab a tiny bit in there, position the LED with a screwdriver (or poker of your choice), count to 5 and it was secure. If I screwed up, I peeled it out, removed the glue, and did it again.
OH, do these with the LEDs on to make sure that you have the light coming through, as best you can.
- Face dots, same idea, just dab glue, press the LED as close to the center as you can, run them to your final one.
- Once they are placed, you have a slew of wires to fold up and put as securely and deeply into the channel as you can. You MUST make sure the wires are securely below the surface because if you go to flatten the back before glue-up and sand through even the tiniest bit of wire... you're screwed. LEDs die and you have a bogus fingerboard. I learned that last year.
If you did it right, you can use wood scrap, made out of the same material as the board, to wedge the wires into place. I didn't do it right, so I used the hot glue and dabbed it all around as minimalist as I could, so the later use of epoxy would flow well.
Then I clamped it down and flooded it with epoxy. The lights were on to make sure they still worked.
ALSO... the end of the power cable, make sure to extend it as needed, cover it as deep into the neck with shrink tube, shrink it, set the wire upright, and let it cure that way.
- When it all cures, you need to flatten the back of the board. I used a card scraper for the majority of it, being very careful around the wire.
At that point, it's basically just prepping the FB as you would for a glue-up.
- Figure out where the hole needs to be on the neck and drill that out. Then test fit everything dry, to make sure it works.
- Mask off everything, apply glue, and clamp it as you normally would.
- Once the neck is a whole neck, just make sure the power can run to whatever control area you have and switch of your choosing. Run the power properly to that switch and you should have lights that go on and off however you have them switched. These LEDs are + and - dependent, so if you keep track of that, you're golden.
That's it! But as with anything, make sure you have all of the specs carefully planned for this. If you have the dots on the side of the face like I do, make sure the material is in the board deep enough for the fingerboard radius.
Do it all as clean as you can, because hidden wood chips or bubbles will reveal themselves in the light.
Worst case scenario to, to keep in mind: If the LEDs get screwed up, you still have dots on the board, so it's not always a total loss.
And you can adapt this a number of ways, should you want different styles or colors of markers.
Hope that helps.