Planning to rework most of the button wiring of the Primary Buffer Panel. For this I use the tool #SimulIDE which allows to run the code for the #Arduino in a simulated #Mega. If everything works out as planned I'll come ahead with whopping 73 buttons and options for more. There's also a new panel incoming that I ordered. This time with touch functionality. Not sure how this will work out yet but I'm hoping to have everything planned out until it arrives.
And this time I'll make a proper wiring diagram with #KiCAD in the end too because just as expected: Two years later I forgot everything and have to backtrack all.

@bekopharm
While I am a KiCad person, you might want to look into other software for making wiring diagrams.

Depending on your actual requirements, qelectrotech might be a good choice.

https://qelectrotech.org/gallery/

QElectroTech screens

@cccpresser appreciate the tip but I'll stick with KiCAD because I know this already and may eventually even go for a custom PCB so I have everything in one [known] place 👍

There goes my plan. This arrived way earlier than expected 🤪

...and I'll need another anti glare foil on this. Yikes.

@bekopharm you could Charlieplex the IO lines to get way more buttons out of that, but figuring out the wiring and logic for that is a real bag of cats, let me tell you.

@TheMNWolf hell no :P

I did check this before.

8x8 is good enough. Going to upcycle some old Cat6 wires for this.

@bekopharm The tldr if you haven't looked into it is you are effectively counting in trinary, where each IO line is either high, low, or high impedance.