I don't know if this video has been posted on here before but the people in the video have perhaps come the closest to building a real lightsaber, so far, out of everybody who has tried. They still got a ways to go but they've made good progress.
Anyway it would be awesome if I could get myself one of these or for that matter if I could build my own. Obviously it takes a high level of skill and is not something you just jump into, but it would be fun to get started.