Piezos seem to be the simplest and cheapest. If there's a cheaper velocity sensitive thingy, tell!
Thanks for the link, kind of what I was looking for. But then I have a few question before I dive into all I have to learn:
I understand that each piezo, after a resistance, is connected to "slot"* in the Arduino board. As a piezo, it will give a different value depending on how you hit it, so there's the velocity sensitivity. Ok. But I need many keys for a keyboard. Being a total noob who didn't know anything about Arduino two days ago, my guess is that you'd need different piezos connected to different "slots" in the Arduino board, so that it gives the computer values such as "piezo 3 gives x voltage", "piezo 5 gives z voltage" etc... and that'd be were programming comes. Is it more or less right? So I'd need a board that has enough "slots" for four octaves (that is, 48).
As you can see, total noob, I'm just guessing, but I'd love to learn from scratch and I'm gonna be unemployed for the whole winter, this seems a very interesting field to learn.
Thanks again!
*What's the real name for that?