Over the years I've managed to build two replicas of Obi Wan Kenobi's film light sabres, though neither of them is entirely accurate. Given the knowledge I've gained along the way, I think I'm ready to build a definitive "hardware" version. While it still won't be 100% in terms of accuracy, it will be better than the two previous attempts. Along the way, I'll be documenting as much of the process as is practical, providing a few tips and tricks for fabricating your own version of the sabre.
What I won't be doing is exhaustively detailing the process. I'll let you fill in the blanks here and there. Who knows, maybe your solutions for some of the challenges in recreating this sabre may be better that mine.
What you'll need to fabricate the emitter is (from left to right): a sink drain assembly, a 1/2" to 1" PVC electrical conduit adapter, a 1" PVC plumbing connector, and a very short length 1 1/4" PVC pipe (not pictured). 
The electrical adapter has to be cut down to size, completely removing the flanged end, and the outer wall has to be notched to allow the sink flange to slide over it. If you look closely, you'll see I've already laid out the drilling points to create the "ring of holes".
Here's the completed emitter. Note the "ring of holes" inside the flange. How many other hardware Obi sabres have you seen with that?
Here's a forward view of the assembly. The white section on the end is what will insert into the emitter. It's styrene T-track assembled around a shaped 1/2" fitting, and a thin walled PVC pipe "sleeve" around that.
Here's a view from the other end with a little more paint. I achieved the weathered brass look by alternately misting black and gold spray paint onto the windvane and back of the neck, and finally drybrushing it with more gold. Unfortunately another of my little mistakes has crept in, and the shoulder behind the "windvane" isn't quite long enough (but it looks okay). The emitter is temporarily attached for reference. I'm also beginning to think the chrome emitter may be too shiny, and I'll have fabricate another one.
Once I'd weathered the neck/windvane assembly the chrome emitter looked much too shiny, so I decided to build a new one. It's assembled pretty much the same as the chrome emitter, with two exceptions. First since it's painted silver, rather than chromed, I was able to include the bevel of the outer sleeve. Second, the flange is no longer made from a sink drain part since it doesn't need to be chrome. Instead I simply used some sheet stryene Dremeled into shape. 
Here's most of what will become the completed sabre (minus the pommel). The forward grip is 1" thick wall PVC pipe. The interior of the emitter end was bored out to accept the 1/2" PVC connector that the 1/2" PVC pipe of the neck slides into. The end was dressed with a ring of sheet styrene for a more finished look. The forward grip slides into a 1" PVC connector, that would be the "spacer" behind the Graflex clamp of a sabre made from replica parts. Behind that, the 3/4" PVC fitting that was attached to the modified resin "gear" just slides into the 1" connector. By building each assembly to fit into the next, it will only require glue for a stable assembly, rather than a threaded rod.
Here's an "in progress" look at the forward grip. The "rings" are sections cut from 1" PVC connectors and bevelled on either side. Once they're mounted, I'll grind the grooves that run the length of the grip. 
Once all the rings were on, and the grooves cleaned up, I ground the grooves that run the length of the sabre. After cleaning that up, I painted the "frag body" flat black and weathered it by dry brushing with silver.
For the first ANH version, I used Plastruct "T-track" assembled around 1" PVC pipe. For the ROTS version, I simply used the part from the Hasbro electronic sabre. For this version, I've opted to use a resin gear. Unfortunately, for the construction methods I'm using, the diameter is too small. Also the "teeth" seem small and the valleys between them too shallow. The simple solution is to build up the "teeth" with 2.5mm square strip styrene (by Evergreen Scale Models). I also modified the clamp end of the gear with part of a 3/4" PVC connector, to accomodate construction that does not require a threaded rod. 
Here's the pommel "in the buff", just to give you an idea how it's constructed. The main part is a 1" PVC connector, notched on the "gear" side and rounded over on it's end. Around that is a thin walled plastic tube (in black) that forms the step under the pommel's "cubes". It didn't wrap completely around the connector, so I filled the gap with some epoxy putty. The very same epoxy putty that was used to form the "cubes" (the gray things on the black tube). A little sanding and it should be ready for paint and "chroming". 
And here's a picture of the completed pommel. Most of it is covered with Monocote silver chrome self adhesive mylar film (available in 4" x 3' sheets at your local hobby store, it's typically used for remote control planes). The rounded over end, where the mylar couldn't follow the curve, is covered in Bare-Metal "ultra bright chrome" (a self adhesive metal foil, sort of like gold leaf). The end cap is a simple 1 1/4" metal hole plug.
Here's a shot of the assembled sabre once the forward grip was cut to length. The "gear" was painted and weathered the same as the frag body, and both were given a shot of clear coat satin. Also pictured is the completed pommel. All that's left to fabricate now is the Graflex clamp. 
Or at least this sabre. I wasn't 100% satisfied with some of the details, so I decided to just finish this off quickly. I scavenged the Graflex clamp from the older version of the Obi ANH which has been stripped down for a thorough rebuild (pictured at the top of this page). I decided to go with the look of the sabre in the "Star Wars Chronicles" book, and left the washer off the forward "transistor" on the side of the clamp.