Internal ZIP drive to external?

It would probably be more trouble and expense than it's worth. The internal Zip drive is an ATAPI device with a 40-pin connection, so you'd need an external case for removable media devices (like a 5.25" optical drive), because the Zip drive's faceplate must be exposed for inserting/removing disks. You'd also need the 5.25" to 3.5" reducing sled with faceplate for the case, which shipped with Iomega retail boxed internal Zip drives, for installing in an empty 5.25" expansion bay. As for the choice of external case connectivity, it would either be FireWire or USB, but if the bridge chip used in the external case doesn't recognize the Zip drive, then it's a lost cause. I attempted to convert an internal ATAPI Zip drive for external use, by installing it in an external USB 1.1 CD-RW's case. Once connected, I got several different error messages identifying "missing" software, which really pertained to the programming of the bridge chip itself. It had nothing to do with Iomega's USB driver, because that driver was already installed in the Extensions folder. The Zip drive is both a mass storage device and removable media device, so you'd want to check the manufacturer's specs for the external case, to be sure that it would be supported. Converting an internal SCSI Zip drive for external use in a SCSI case is a straightforward swap with no problems, but that's not the case with an ATAPI Zip drive. As I wrote at the outset, it may not be worth attempting the conversion, especially since you can find used, external Iomega USB Zip 100 drives for very little now. The first generation of USB Zip drives had an external 5-volt power supply, but the newer ones are smaller, bus-powered devices. The low cost and convenience of using USB flash drives has made the more expensive Zip disks less popular for backup usage now.