[gigaflop]

Here's a keyboard PCB I designed a while ago: https://imgur.com/gallery/lZglox7

I followed the ai03 tutorials (https://wiki.ai03.com/books/pcb-design/page/pcb-guide-part-1...) to design the MCU area of this (The 32u4 and supporting hardware), but if you look at the traces, you can see that the switch matrix is dumb-as-bricks and can easily be replaced with some kind of handwiring.

Don't try to replicate the diode banks if you want sane wiring. The linked tutorial assumes someone is designing for function instead of form.