^ Rob, the way it is written suggests that he wants to design it himself and then hand it off to a luthier to have it built.
Having a library of pre-drawn parts is convenient, at any rate, to help make sure headstocks properly occlude the backside of the tuners, pickup routes are properly sized, and bridges don't hang off the end.
I use eMachineShop
to start all my designs, and then Dassault Systeme's DraftSight
for finalizing the drawings of anything I need to have machined.
Both are free. eMachineShop is very crashy and buggy, but is so easy to use and design with, I have a hard time putting it down. It can also import and export DXF drawings. DraftSight is a much better program, but is more like a traditional CAD program, and so is more complicated to use. It isn't as much fun, to me.