This project probably does not warrant a PCB (it's kind of a joke/toy), but I designed one anyway. I put together a pin-for-pin copy of the hand-wired prototype. This should be functionally identical to the prototype with the inclusion of some power select jumpers and extra pin headers. It's a two layer board and it's well under 100x100mm so it should be really cheap at most manufacturers. I'll include this in my next order.