Dont throw away that old PS/2 keyboard just yet. If youve got a box of Lego bricks and a bit of free time, you could make an amazing DIY input device like this one.
Obviously youre going to need some specific piece to copy Jason Allemanns creation. Its a brilliant combination of Technic bits and standard Lego, and its every bit as functional as the original keyboard it was built from.
Any membrane keyboard should work just fine for the build. Start by removing the plastic exterior, then peel away the circuit board and the sensor pad. Youll want to take them out somewhat gingerly the USB or PS/2 cables on cheap keyboards arent always all that securely attached.
Next youll need to make a simple surround. Jasons build uses two-by and one-by plates, snapped unsurprisingly into a rectangle thats roughly the size of the original keyboard. The next layer is the fun part: the interlocking Technic pieces that support the keys. The membrane provides the bounce, and all the Lego needs to do is glide up and down freely and support the flat key tops.
If you look closely at the images Jason shared on his blog, youll be able to see how the mechanical bits fit together. Tracking down printed tiles with letters might be the trickiest task, but theyre available online at a number of specialist Lego shops (like La Petite Brique).
As for the finishing touches, those are up to you. Just about any smooth plates will do, and the best part is that you can always change them later if you want to. Its sort of like a low-tech, Lego Optimus that way.