The PQI i810 claimed to be the smallest drive on the market at one point (I’m not sure if they still do). But having just made a chicago screw compact keychain, I no longer had a spot on my keychain for it. Small wasn’t small enough. Also the spring clip that holds the protective housing in place when expanded or contracted had just broken so I decided to do away with the housing completely.
I was a simple job with needle nose pliers and a utility knife and now I have a wallet-size USB drive: