Well, I was thinking about building my own lightsaber in good ol' jedi way, too!
I'm just a moderate SW fan myself.
Easiest way, I thought it might be buying a replica or toy - but they tend to be very large. Even the expensive .45 replicas might be too large. If I do build, I'd like to go for smaller size - perhaps just enough to put 2 cr123a.
Other than that - it's got already a great switch in its design, so other than coming up with some cosmetic decision and compromising - I think this might be an entertaining project to work on.