The Vader ROTJ is by far my favorite Vader saber.
Another good site to read about the pieces used in constructing this saber is The Parts of Star Wars
. As its been pointed out, it was made from a Luke ESB stunt saber. It's basically a Graflex tube with a few added greeblies. It shouldn't be too hard to add electronics to one if you attach the hex bolts differently. Maybe just cut off the heads of the bolts and glue them on.
Now comes the fun part. Getting accurate pieces to make one is not easy. I own a fan built one that can be seen in my showoff thread, but I have been slowly aquiring parts to build one myself. Elvistrooper isn't making his kits anymore and it's almost impossible to find an accurate ball catch. No one really knows what the plug in the bottom is, but a chrome tire valve looks pretty close. I've been lucky enough to find two emitter shrouds (one aluminum and one resin), an aluminum D-ring "post" for the top of the saber, and a resin control box. The grips and Kobold (rear) D-ring can be purchased from Blast-Tech.
If you're a DIY kinda guy, here's an execellent tutorial
by WadaYado, the guy who built mine.