The only concern that I would have with the fiberglass resin is that it drys pretty quickly. The system 3 I used took over 48 hours before it was fully cured, which gave it plenty of time to let any moisture or air bubbles escape, and it dried rock hard. Moisture shouldn't be an issue, as you live in a dry climate vs the swamp I call home. I just hope its hard enough.
One of the reasons I took on this $100 challenge was to try different and less expensive methods. I figured trying this fiberglass resin is a pretty good test. It's $15 a can, and available at the local Lowes or Home Depot. If it works, perhaps we'll be able to save some money next time a fretless build is done. If it doesn't work, we'll know not to use fiberglass resin
I figure the worst that can happen is that as I string up the bass, the neck relief introduced will either crack the resin, or make it pop off the fingerboard. At least I'll still have a prop, albeit a non-working one. Or I'll just sand it off and try CA glue. I did see some areas that seemed like either some moisture did get trapped, or an air bubble, or perhaps just a different curing level, or some kind of difference. Time will tell.
And yeah, I hope it's hard enough as well. In any event, if it does work, but is somewhat too soft, I can always sand it down more. It's about 1/4" at its thickest area, so that's enough for a few re-levels.
Here's what it looked like after I pulled off the tape.
And after I sanded it to the radius with 80 grit.
And wiped down.
That resin dust is brutal. I wore a dust mask during the process.
Didn't I recently say that I'd never work with fiberglass resin again after my last build?