Thread a piece of elastic long enough to go around your chest through the circuit, between GEMMA and the NeoPixel Ring.
To keep it from obscuring the center pixel, cinch the elastic in one spot with a few stitches, then align that spot with the circuit.
Use a safety pin or velcro to secure the strap.
Use a JST extension cable and 3xAAA battery pack tucked in your pocket for many hours of glow time. We experimented with using a coincell battery pack as well, but it only lasted for about an hour.