ATMega328p development board with built-in 8x8 matrix, HT16K33 driver chip, and battery power.
Shop Link: http://shop.matchfire.net/electronics/led-matrix-pendant.html
To view and edit the PCB, the PCBWeb program is required. It is free and available at http://www.pcbweb.com
Several basic programs included to get you started on your own code.
The LED Matrix Pendant includes a 5v step up voltage regulator, with a working input voltage from 0.8v to 5v. Exceeding 5v can cause damage to the device!
The low input voltage should allow it to squeeze a small amount of power out of standard Alkalaine batteries compared to the DigiBadge V2 (Which will shut off at 1.8v), but the amount will be fairly small as voltage drops sharply after an individual battery goes below 1v.