Oddly enough, Seymour Duncan himself, supplies some of the best info.
Go to the home page, click on:
Support>Seymour Q & A, and start reading. There's more than enough info there to design and build a pup. If thats not enough, there's a good book called "Pickup Winding" or such by Jason Lollar.
Do an Amazon, or Google search, or get it from Stew-Mac.
It is great for making a winder and has some good stuff (and diagrams for bobbins). It is a good book but humbucker info is a bit limited. Probably because there's more work and parts involved. Maybe Its just me.