Helped my friend with a plasma pistol cosplay prop with an Arduino nano controlling some APA102 LEDs in two strips of 10 side by side.

It animates a slow-to-fast forward sweep along a color axis from blue green to a more teal with increasing brightness until it reaches full brightness and speed which is flashes through 10 times before flashing all the LEDs as if it fired.

I'll post a video of the animation later; not sure how well that description works.
#MakeAllTheThings