While coverage of the official Defcon badge has been pretty heavy, there was a badge that was far more exclusive and talked about way more. For the last ten years at Defcon a group of hackers known as Ninja Networks hosted an invitation-only party for selected attendees. For the 2009 event, [cstone] and [w0z] created an electronic badge which acted as the ticket to the party. The badge is based around an 8-bit Freescale microcontroller (MC9S08QE8) which drives 10 individual 16-segment HIOX-format LED displays.
The custom PCBs were manufactured by 4pcb, but all other assembly was done by hand with a huge team of volunteers in Boston, Los Angeles, and Las Vegas. Assembly space for this effort was provided by Redwire and Angel Valley Media. More than 500 badges were created. To help fund the effort, the Ninjas took on internet privacy company XeroBank as an event sponsor.
The assembly process is detailed in the video below which highlights a few interesting DIY techniques including using a $30 Target hotplate as a reflow oven.