A few years ago, I got challenged by Zenn Canters (https://www.facebook.com/zenn.canters) to come up with a safe way to have fireworks on a guitar without risking injury and/or damaging the guitar. The worst actually happened to someone, to the guy he replaced in the band he is in, when he got confused and set off the fireworks in the wrong direction, damaging the finish of the guitar neck and causing some panic on stage.
So, after taking some measurements of my Tokai headstock, I designed a prototype and 3D printed it. I used a battery compartment for a 9v battery, although it would be perfectly doable to 3D print one. One of the power wires is interrupted by a momentary switch, and then they connect to a speaker style terminal, so the wires for the fireworks detonator can be easily hooked up. The parts were printed in ABS and acetone vapor smoothed.
It fits really nicely in the headstock, and in the dark it will be practically invisible.
Finally, here it is in action.
Keep up with Zenn Canters at https://www.facebook.com/zenn.canters. He's an awesome guitar player, and a really cool guy.
If you want one of your own, you can contact us at firstname.lastname@example.org or on https://www.facebook.com/JdMusicLabs/