*cross-franchise*

Ye canna change the laws of physics Capn!

As everyone has pointed out a black lightsaber is categorically impossible.

But then so is extension and retraction effects with a single in-hilt LED - ye canna change the speed of light eh?

Yet we can get a kind of PSEUDO extend/retract effect through PWM drivers and 'Corbin-type' striated diffuser film so maybe we should ask if the ILLUSION of a black blade is possible?

Not through our normal blade-lighting methods I'm certain...but maybe if one used multiple [probably moving] tubes with slits [M-M experiment eh?] to create reinforcing interference patterns in just the 'right' way one might, REMOTELY possibly, be able to create a 'dark' interference pattern in what would APPEAR to be the 'core' of the 'blade' tube???

...I suspect even IF its possible [and i'm not sure it even is] it would be a ridiculously tricky and time consuming to R&D and possibly expensive, certainly not duelable [any shock whatsoever would ruin the absurdly precise alignments] and just not worth the bother for an optical illusion in a 'toy' imo...but kudos to anyone who can do it...I wouldnt try.

Just do yourself a favour and get a 'black' smoked poly blade and white LED...yeah its technically the opposite of TFU but similarly distinctively different from normal lightsaber blades so close enough for me anyway...or if you are really just into looking Sithy get a smoked poly blade and put a red LED for a 'Death blade' which looks even cooler imo.