I have a hitbox layout on my Qanba, but I want to cut another hole in the plexi and panel so that I can have the default layout and 1 extra button to have Left mapped to, which would be right above right so I could get 100% EWGFs on both p1 and p2 side.
So you just want a extra left button? Sounds reasonable.
How to cut holes both both the metal and plexy? You will need a drill. Preferably a drill press but you can also drill by hand.
Hole Saw will work, but you got to be careful on the plexy. You can also use a metal cutting step bit.