A ton of NeoPixels powered by an Adafruit Flora or Adafruit Circuit Playground Express, attached to a custom pleather harness.
I dreamt up an LED wearable that I could throw on over a tank top or a long sleeve shirt or perhaps even under a piece of clothing. It would be lightweight, not too bright, and be super comfortable to wear. The problem with incorporating LEDs into a big scarf or coat is that it can be uncomfortable if it's a warm, dark night.
The first iteration came together the week before Burning Man 2018. I made a harness out of elastic and strips of pleather and then worked on a plan to cover it in LEDs. I began with some surface mount dotstars and quickly realized that using NeoPixels would be much easier. I decided on using black wire for the entire piece and braided wire so as to not mix anything up.
I shared the first iteration on the 9/26/18 Adafruit Show-And-Tell hangout (@10:41).
For more information, see the Adafruit LED Harness Bra guide or the video here: