Here's the bad news: Building a working lightsaber is probably not in the cards, at least not in a way that resembles the weapons in "Star Wars." The good news is that we can do some cool stuff with light — including making individual photons interact with one another — but making a working lightsaber is beyond our capabilities. So as "Star Wars" looms in front of us, we figured why not talk about how a Jedi makes one?
To answer this question, we have to look outside the realm of the films, which gets into some shady territory as far as what's canon is concerned. But we know that constructing a lightsaber is part of a Jedi's training — Darth Vader confirms as much in "Return of the Jedi." He sees Luke wielding a brand-new green lightsaber and observes that Luke's “skills are complete.” Presumably, a Jedi trainee building a lightsaber is sort of like taking your last final exam before graduating high school.
The hilt of a lightsaber is typically metal, although other materials have shown up in some supplemental Star Wars material like "The Clone Wars animated series." Inside the hilt is a power source and an emitter to create the light blade. Most supplemental materials mention crystals, which provide the lightsaber's power and color.
Assembling these components in perfect alignment to create a lightsaber is next to impossible unless you wield the Force. Using the Force, a Jedi (or Sith for that matter) can arrange the internal components of a lightsaber so that it creates the desired blade. If misaligned, the internal arrangement could cause the hilt to short out or even explode.
Wielding a lightsaber is also pretty tricky. Jedi and Sith use the Force to become effective warriors with a lightsaber — your average schmoe is almost as likely to lop off his or her own arm. Come to think of it, losing an arm seems to be a theme in the Skywalker family, so even Jedi aren't immune to this.
Sadly, lightsaber lore is firmly in the fantasy camp. But that doesn't stop us from finding new cool things to do with light, from creating 3-D projections to controlling the movement of atoms, which we mentioned in the video above. That's almost as cool as the Force, right?