Just a quick update on this project of mine :)

I haven't forgotten about this project, however a lot of the development for the software of this one is intertwined with my #DIY SamplePad Controller project as well; both will use the same code to read the pads and then just process them differently. This project's Arduino Mega uses a single serial port to pass data to the Pro Mini for turning into MIDI output, and the SamplePad's Mega uses four software serial ports for sending commands to four DFplayer mini boards.

There's a strong chance Id like to leave an option for MIDI output on the SamplePad in the future, so it makes sense to develop the Megas code for both projects as one, with options to turn features on/off in the sketch.