Do you have a particular shape in mind? Remember, if itís bigger than a standard size bass you may have a hard time finding a case to fit it. Things need to be hefty and strong on a bass, including the neck joint and bridge area, and the bridge sits way back toward the butt end so make measurements before you cut. You should have a long straight-edge for lining things up. Also, I personally donít like wide necksÖ especially on 5 or 6 string basses. Itís just too difficult to get my thumb around an excessively wide neck. Making a neck is a big jobÖitís far easier to purchase a neck than to make one from scratch (especially when it come to the truss rod). Here are some common venders for necks: Warmoth, AllParts, Guitar Nucleus, Mighty Mite, WDMusic, and Carvin.
The wood for the body should be fairly hard, but avoid oak! Oak is not a good choice for any guitar! Oddly enough, I've read that Teak is good for necks but lousy for bodies.