Two Daft Punk outfits with about 70m of EL wire coupled with arduinos plugged into LED arrays stuck inside bicycle helmets. Turned out pretty good:

https://www.youtube.com/watch?v=uHrWllxRLgQ

Wrote the step-by-step and uploaded the code onto Instructables, it's still there ~15 years later:

https://www.instructables.com/How-To-Make-Two-Daft-Punk-Outf...

I made them with my girlfriend (now wife/co-founder) for my 30th, was lots of fun.