That's what I was on about. I would have a plug made by CNC or Rapid Prototyped so that I could make the mold and keep the original (dead accurate) plug save somewhere.
I'm doubting that you could make the plug yourself, but personally with a complex 3 dimensional like this, especially with dimensions that have to be so accurate, I'd ship it out to be done. I think that if you take into account the radius of the fret board, the distance between frets, getting a constant and uniform shape down the length of the fretboard etc then it'll be a nightmare to make the plug yourself. Not impossible, but still a nightmare.
Anyway, keep us posted on this as it seems like a very cool idea. I'll help where I can as I want to see this
Kaj