When I started designing this project, I quickly though about Cherry MX switches (or clones): they're cheap and widespread. The blue ones also have a nice cliky feeling that I like.

As for the wiring, I settled for a simple matrix with diodes to avoid ghosting. An ATMEGA32u4 scans the matrix and acts as a keyboard to send the matching keypresses. I based my design on the infos found here.

No time for a PCB for the first iteration, everything was hand-wired.

Don't mind the yellow print, it was a trial run. Next picture shows the later grey version.

All wired and working. I'm not really 100% happy about the keycap/cherry MX interface... I'll redo them at some point.

Here's a small video showing the keyboard in action. The laptop on the left is running yaDSKY and is connected to my keyboard, the one on the right is running yaAGC with a virtual display. Both are connected to the same network.
I'm running a simple lamp test program (V35E).