If you have the requisite woodworking skills, I am confident you could build a pair of speakers. Though soldering a bunch of components together may seem a bit intimidating, it's actually pretty easy. As long as you can read a circuit diagram (or learn) you shouldn't have any trouble. If you make any mistakes, it takes about three seconds to desolder them and you can try again.
Here's a site you might be interested in with some good designs (ooheadsoo reccommended this to me, though I never built any of the speakers):
Dennis Murphy loudspeaker designs
I was intimidatd by the idea of building speakers when I was in the market, and now I wish I wasn't. Although I feel my Mission M71s are some of the best commercial speakers under $600, I can't help but think I might have gotten better for the same amount of money. Having now learned to solder (I shouldn't really say learned; it takes about ten minutes to learn how to get started), I strongly encourage you to go the DIY route. You will get a better speaker than you would have on the commercial market, and you will have the satisfaction of having built it yourself! I say go for it!
As an aside, I'm building a pair of fullrange TQWP (Tapered Quarter Wave Pipe) speakers this weekend using a pair of $10 fullrange drivers from RadioShack and spare wood I have in my basement. It should be fun! These will probably be relegated to TV duty downstairs as I really doubt they will sound as good as my Missions, but I'm really doing it as a fun little project anyway so it doesn't matter.
Btw, why do you want a three way speaker? The more crossover circuitry the harder it is to end up with a good speaker IMO, and I also don't think you really need three drivers to get fullrange sound. You actually don't necessarily need more than one driver to get from around 35 hz or so all the way up to 20 khz. See
this design, for instance. I, personally, love the fullrange sound. No crossover = smoother sound (in general)! Fullrangers also have phenomenal imaging and soundstaging abilities.