HelloDrum-arduino-Library VS arduino-midi-recorder

Look Mum No Computer built a simple recreation of the Kraftwerk electronic drum pads. A more modern approach might be to use an Arduino.

I'm using this library. He has circuit diagrams here.

Okay I'm half tempted to leave it as Tuscan (but only half =)

Adding a button that you can press to inject a MIDI marker is an interesting idea, for my own use (once I turn it into a non-breadboard version) is to just hang off the back of my controller so that wouldn't be a convenient place to interact with it, but if you have it just sitting in reach, I can see that being super useful.

I've filed https://github.com/Pomax/arduino-midi-recorder/issues/3, if you want to hop on that, you're more than welcome.

As for tuning: there are many, but it really depends on what you're playing, so if the arduino was driving its own little mini-synth, you'd probably want to add some tunings that would allow you to at least match the various tunings you'll find in any custom-tunable stage piano.