His solution takes an off-the-shelf high-powered reader, (such as the HID MaxiProx 5375), and makes it amazingly portable by embedding 12 AA batteries and a custom PCB using an Arduino Nano to ...

[Rodot] wrote in to tell us about the Gamebuino, a very nicely designed and easily reproducible version of his handheld Arduino gaming ... lithium battery, a micro SD card, and I2C expansion ...