I decided to build my own arc reactor, as the ones made by others online were either too bulky, or required some silly way of attaching it to the chest.
Being familiar with the Arduino platform, I discovered the Lilypad version and it's associated sewable components. To top it off, the Lilypad is circular, flat and perfectly small enough to fit within the ring of LEDs. The only downside is that the Lilypad LEDs don't support the Analog Write function, which would have allowed them to fade on and off.
Regardless, the entire circuit (minus the battery) is washable, and the LiPo battery has enough juice for at least 6 hours of continuous use.