Case is made from the numpad of a dead Corsair K70 mechanical keyboard. Corsair, in their infinite wisdom, made the numpad easily detachable with the simple application of Dremel and force. Underside is taken from the plastic from the K70 as well.
Handwired with assorted diodes I dug out of a RadioShack components box I've had lying around. They're not uniform or pretty, but they work just fine.