I'm ready to begin getting the materials together for my first build soon. I just have a few questions regarding some of the parts I'll be looking into getting.

32" scale/22 fret (neck-thru)
J-bass spec neck
Swamp ash wings
Maple neck
Headless

Attached is a crude 3D model to give you an idea of what I'm building.

1. Nut. I'm making my neck pretty much to J-bass specs (but 32" scale/22 fret). Should I get a fender replacement nut or make my own? If so, bone, tusq?

2. Fingerboard. Again, J-bass specs/rosewood. Pre-radiused, pre-slotted? Since I'm going a shorter scale length and more frets I guess I couldn't go for a pre-slotted Fender fingerboard.

3. Neck. It's a neck-thru design, but I can't find a blank for a neck thru anywhere online. Will it be best just to go down to the local lumber shop and have them cut me out a blank?

4. Tonechambers. Can I rout these from the back. I was thinking about making them 1" deep. The body is 1-1/2" thick. Depending on the time I have and budget, could I leave these exposed or would I need to cover these with a laminant?

5. Pickups. J-bass, active electronics. I want to keep it simple, probably just vol/vol/tone controls. Any recommendations on how I'd go about this or any pickups?

My budget for the whole project is about $500. I already have the headless tuner ($100). I know this is a lot to be discussing all in one post, but I'd appreciate anyone's input on any topic.

I'll let others comment on most of your list. Just three quick comments:

- get a book
- read through the sticky at the top of this forum, and its links
- you can get a pre-radiused and slotted standard 34" scale fretboard, 24 fret, and cut of the top (so the nut slot disappears, 1st fret slot becomes the new nut line, 2nd slot becomes the new 1st slot, etc.), and it will be a smidge over 32" scale. And you'll have a max of 23 frets to work with.

there are a few places to get a neckthrough blank, check out gallery-hardwoods, I have only heard good things about them

Thanks. I do have the book Build Your Own Electric Guitar and Bass which has been very helpful thus far. Its basically just the small stuff thats giving me questions.

That sounds like a good idea, cutting the top frets off a 34" board and working with that. I'll give it some thought.

Make this thing! The 3D looks great!

Nut: forget it. Use a zero fret, and the top clamp of the headless unit will take care of the string spread. Simple, easy, superb.

I like to make the wood stuff myself, so I have no real advice on sourcing.

Yes you can rout form the back, no probs. You need a cap over them, of course.

Why active electronics if you only want vol/vol/tone? There are plenty of very good passive, simple pups out there.

The only reason I was going active was because this bass would be used a lot for travel and I'd like to just be able to plug some headphones in and play. Any way of doing this with passives? (btw: I'm an electronics idiot)

Looks fine, but the lower horn will stab you in the thigh if you try to play it sitting down.

The only reason I was going active was because this bass would be used a lot for travel and I'd like to just be able to plug some headphones in and play. Any way of doing this with passives? (btw: I'm an electronics idiot)

Yeah, and you seem to be worse than me! No, seriously, I had the same thoughts for a while, but found that I was way out of it. Whatever I tried, it didn't work...

To be able to use headphones directly out from the bass, you need a built-in headphone amp. You can find a few on the market, pretty small and simple to install. I know there is >1 in the NAmericas, but I can't remember the name, and then Bassixx of DE has recently presented one.
They can be fed with passive or active pickups/preamp, so you're free to choose the rest of the electronix.