Just in time for the movie of the decade, [Allen] from [Sufficiently Advanced] has built a real working fire-based light saber. And it’s awesome.
He started out with a replica light saber and designed his own 3D printed enclosure to house a small tank with a syringe valve that goes inside the handle. This allows him to fuel it with a mixture of methanol and acetone, using butane as a propellant. He learned how to do this from [Tesla Down Under], who has some fantastic projects — most notably, flamethrowers.
A nichrome coil provides ignition for the flame, and after he got the pressure just right, it produces a pretty awesome, albeit skinny, flame-saber.