Every button in my build works as intended. I’d be more than happy to share it with you guys, should you need it.
Regarding the power supply wiring, I had an electrician friend of mine wire this up, so I really don’t know the exact specifics, and it’s also made for european outlets with protective grounding.
The IKEA table is quote strong, believe it or not, but I added pieces of 1cm thick plywood underneath the top where the joysticks fit, since they are the ones taking the most pressure. I did not strengthen the top underneath the buttons, and it has worked so far, but if you were to build one, make sure to strengthen the entire bottom of the top finish.