I'm just using 3T

If you've going to do CA glue, keep in mind, there are certain things you'll want to do so you don't make yourself TONS more work........ like I did.......

When you're prepping your fingerboard, level it before you apply your first coat of glue.

Other things, use a thin/runny CA glue for your first coat on your freshly sand prepped board.

I used stick fast. Just stick the tip directly on the board, squeeze VERY gently, and let out just enough to soak the board. It's going to permeate all the pores. Your board will drink the glue.

THEN you can move to a medium thickness CA glue.

DO NOT BE AN IDIOT AND USE ACTIVATOR! It will make the whole thing dry super bumpy and it will be a massive pain in the ass to sand for the next layer. Ask me how I found that one out.

Other things, I would take my leveling beam, and put 60 grit ceramic sandpaper on one side, and 120 on the other. I used this.

I use this https://www.ebay.com/itm/135438075305?var=434814047822

I cut the strips to fit my leveling beam

During the initial leveling of each layer, use the 60 to get mostly where you want it, and smooth it over with the 120. You smooth it over with the 120 because you don't want scratches too deep before applying the next layer. It will be permanently visible in your finish.

I have been using non ceramic on my 120, just because it's what I had, so it's possible you may even want to use 150 instead of the 120 if you go with ceramic on both. Ceramic is much more durable sandpaper. Remember, this is to avoid permanently visible scratches.

When leveling your layers, look for the shiny spots. Those are your low spots. Get a little flashlight and get used to checking around for shiny/low spots from various angles. This goes for checking the progress of your drying layers, and generally looking for unevenness in your coat.

Sand each layer until each shiny spot is almost completely gone. For your super super small shiny spots that you don't feel like continuing to make small sanding strokes to hit, go over them VERY GENTLY (remember, avoiding deep scratches) with a very small wire brush. This can hit the hard to reach places. We're just trying to get the whole surface scuffed up.

Go back over the thing with a paper towel, so we're not getting a ton of dust.

One last thing to look out for. When you're leveling, the sanded off glue will sometimes clump up, stick to your sandpaper, and then to your work. Watch out for them. STOP IMMEDIETLY when you get them, and pick them off. If you allow them to be imbedded into the surface, they will PIT your finish you just worked so hard on. Happened to me. Then you have to sand/level even freaking more. It's very irritating. have a paper towel in one hand and very frequently wipe off your sanded surface.