Msaleiro from instructables.com has built this open source mechanical keyboard he has been working for the last 2 years. It may looks like an ordinary keyboard but it has many features embedded. To check them follow the link below. He writes:
It looks like a computer keyboard, and it is, but not an ordinary one. It’s story and hidden functions add a lot more to it. “Under the hood” you’ll find that this keyboard has:
SMK Alps Mount switches
Special commands to record up to 12 macros
Internal USB Hub
and many more.
HacKeyboard – open hardware mechanical keyboard – [Link]