Tony Firshman runs his own QL repair company
and recently donated some excellent QL related peripherals from alternative OS's to slot doublers and disk controllers.
Thanks Tony!
A brief list:
CST QDISK disk interfaces (3)
CST floppy/SCSI interface
CST slot doublers (2)
GST 68K/OS board and ROMs
Qontrol interface
QL MEDIC interface with associated floppy drive. Rare, etc, because the interface has a CASE!
MicroPeripherals disk interface and floppy drive rebadged by Sinclair/
3.5" floppy drives
PCML twin-drive floppy unit that I've converted to be a Teledisk
Harprom 192K ROM expander board that I know nothing about