Glowing Hat

I glued 100 WS2812 NeoPixels to a hat then mapped them in 3D space


You will need:

I hot-glued the lights to the hat, turning in a random(ish) direction after I'd glued-down each one, attempting to move towards empty space each time. I also managed to stick 2 or 3 of them on backwards because I'm an idiot.

I cable-tied the Pi to the power-bank and wired everything up, producing something you absolutely would not want to try to take through an airport:

not a bomb

The data line is connected to pin 21 (physical pin 40).

Installing the software

From a box-fresh install of 64-bit Raspberry Pi Debian 12 (bookworm) (Note: I turned off device-filtering in the Raspberry Pi imager because it didn't want to let me have Bookworm for my Zero):

Set hostname

sudo raspi-config nonint do_hostname glowing-hat
sudo reboot

Install git

sudo apt --yes update && sudo apt install --no-install-recommends --yes git

Get this repo

git clone

Install everything

cd glowing-hat

Mapping the lights

Once everything is assembled, you need to take lots of photos, and do a load of analysis.


The five buttons are are mapped as follows:

  • A: cycle through the available modes
  • B and C: turn the brightness up and down
  • D: display the hat's IP address (if an Oled screen is available)
  • E: hold for one second to restart the systemd service
  • A and D: hold both of these for three seconds to reboot the whole Pi (sometimes things get really stuck)


A mode needs to inherit from Mode, and should expose a run method, which loops forever and does something with the lights. A mode needs to be included in this list in order to be eligible, and then the mode ordering and per-mode preferences are defined per hat - here, glowing-hat is the hostname to which this list will be applied.