QPlane
Qplane is a backplane device, designed by Zeljko Nastasic and marketed by Qubbesoft. Designed to help mount a QL motherboard in a PC case, this device took its power from the PC case power supply.
QPlane had 3 expansion slots, allowing you to add memory expansion, disk interface etc to a cased QL. Simply connect the female slot to the QL's standard expansion port, and then you have 3 further expansion slots to hold your QL interfaces.