Instructables user cubeberg has posted about how he turned a cheap Tron Identity Disc into a prop for his daughter.

In this Instructable, I cover modding the store-bought Deluxe Identity Disc to an upgraded version with 64 leds, controlled by an AVR MCU. The upgraded version is costume-ready and would be an excellent addition to your Tron costume – it’ll also look great on your desk/dresser/etc.