Chris Faye made an awesome LED top hat.
The hat uses an 8×32 LED matrix in 4 sections that run in parallel using the FastLED library. While battery life does depend on the brightness of the LEDS, Chris did wear the hat and had it running for about 5 – 6 hours at the Edwardian Ball without needing to change the batteries.
There is some good discussion on this forum thread about trouble shooting some issues where the LEDs were dramatically slowing down after about a minute.
Code for the project has been published on GitHub.