I'm so stoked for Octojam, I put together a little keypad, inspired by the COSMAC VIP's keypad, to play this year's games with:
It's a BM-16A PCB and case, purchased from KPRepublic. I had to solder in switches myself (I put in some Zealios Zilent switches I had lying around for a tactile feel). The keycaps are a DSA Mono-Color keyset for an ortholinear layout from Pimp My Keyboard (Signature Plastics); the DSA profile means the keycaps are all the same height, and the ortholinear set comes without sublegends on the numeric keys.
I then programmed the keypad using the open source QMK firmware, and mapped the keys to the Octo layout (ie. 1234qwerasdfzxcv).
Time to play some CHIP-8 games!