"How do I build my own bass guitar?"
Guild of American Luthiers http://www.luth.org/
The Association of Stringed Instrument Artisans http://www.guitarmaker.org/
Guitarmaking: History and Tradition, by Cumpiano/Natelson
Making Master Guitars, by Roy Courtnall
Classic Guitar Construction, by Irving Sloane
Steel String Guitar Construction, by Irving Sloane
The Steel String Guitar, by David Russell Young
Animal Magnetism For Musicians, by Erno Zwaan (great resource for bass construction)
Lutherie Tools: Making Hand and Power Tools for String Instrument Building
Lutherie Woods and Steel String Guitars, both by GAL members and staff.
Guild of American Luthier's Big Red books. There are several volumes now, containing a wealth of information from experts and amateurs alike.
Allied Lutherie Ltd. has the center hole design available;
PLA9 Kasha/Schneider, original, 2 sheets (drawn by Stuart Adamson).
Also other plans by Stuart Adamson meant more for the beginning or experimental luthier.
PL26-center soundhole-drawn by Stuart Adamson
PL27-offset soundhole-drawn by George Majkowski
P O Box 13301
Des Moines WA 98198-1005