Inspired by http://www.thingiverse.com/thing:1043977
This is a 4x4 equivalent to be used with an Arduino Pro Micro. Made as a Macro keyboard for my wife, so she can use a few shortcuts handy while using her Wacom keyboard.
You can search ebay for "Keyboard Keys Metal Panel SPST Machine Pushbutton Switch". You can even simply buy the plate and use different switches (like Cherry MX ones).
Pictures show an early version, I had mistakenly measured the inner dimensions of the switch plate instead of the outer. It still fit, but not very comfortably, the files here are for a better version where everything fits nicely.
A simple code sample (and the one I actually used in this project) can be found here: https://github.com/nariox/4x4arduinokeyboard
- I didn't draw the holes for screws, I just drilled some on top, but it's not extremely strong.