Made them with those, one per boxe, plug and play, I actually have 3 of those button boxes, last one not in the pic, 36 buttons
https://www.ebay.com/itm/2X-Zero-Delay-Arcade-USB-ENCODER-PC-TO-JOYSTICK-FOR-5PIN-JOYSTICK-2-8MM-BUTTON/261481024864
Thanks
Marc..