Retrology Gaming Bits - The 3DO controllers were unique in that the system base unit contained only one controller port and the controllers could be physically daisy chained together via a port
3DO HORI 6 Button Controller vs SOLDIER PAD - YouTube
Performance 6 gamepad repair : r/3DO
REAL PANASONIC 3DO GAMEPAD 6 CONTROLLER CONTROL PAD MODEL P-1201 PERFORMANCE | eBay
Panasonic 3DO Controller Boxed FZ-JP1X Japan 1 Week to USA | eBay
Panasonic 3DO Game Pad 6 Controller Control Pad for Sale