Zzarko and Msolajic developed a file generator to make EPROM files for a Magic Desk compatible cartridge. The generator includes a system to make the menu for the cartridge. A schematic for making the cartridge is also included. The system can use 512 KB, but if you want to use it in VICE the limit is 128 KB.
Download: MagicDeskCompatibleCartridgeGenerator-2.0.tar.gz
Website: CSDb