AVTOKYO 2015 Electrical Badge
Japanese ATmega328P LED attendee badge
AVTOKYO's official 2015 badge page says the conference made an electrical badge for attendees, with an AT-MEGA328P-PU, eight 5mm LEDs, two push buttons, 16 MHz crystal, resistors, capacitors, IC socket, coin-cell holder and battery, public KiCad PCB design, and public Arduino program.