A very limited quantity of the new RetroUSB32 (KADE compatible) are up for sale.
These klever pieces of hardware enable you to connect any custom joystick to a PC, MAC, Raspberry PI, etc…
This board can be entirely customize to your needs. You can simulate a HID keyboard, an HID joystick (or two) and also give some feedback like a led or a rumble.
This is ideal for your MAME cabinet!