Who doesn't want a light saber? There are lots of projects using neopixels (and products as well). Here's a silly "saber" (dagger? scalpel?) using a neotrinkey. It won't impress many, but it was fun to put together. When you put this in as "code.py" on a neotrinkey, you can plug it into any power source and it will first blink "hello" in Morse Code, then touching pad one will choose a random color. Touching pad two will "ignite" or "douse" the saber.
I originally wrote a saber for a Gemma M0 with a 30 neopixel strip. I didn't like blinking all the saber's lights on/off, and rewrote it to ignite/douse more slowly to make it realistic (as realistic as an imaginary weapon is, of course). Then... I thought it would be just as fun (and more portable) to do the same thing on one of my beloved neotrinkeys. So here it is:
(And, yes, I know it isn't a lightsaber. :)