Here are pictures of my devices used for testing the Port-a-puter
Click to enlarge the roadless version of a USB flash drive. The card reader was something like $9.00 and the CF card was maybe $12 or $20, special at that time. There are shorter USB extension cords available out there.
Below, the CF card in its protective PCI adaptor card is on the left The connector end is inside the adaptor shell. The genuine thumbdrive (SanDisk) is on the right. The split ring is fairly flimsy looking to me. It won’t be easy to replace that as the space to switch rings is tight. I added the “carabiner” clip to make it less likely to misplace or lose. The USB connector is slid inside.
Lorelle VanFossen illustrates a portable drive.