I recently saw a USB memory card fitted into a Full sized regular Zippo. (Spanish flea's creation).
Although liking the idea, I set out to do a version more in keeping with my preferences. After discussing it with a friend, and pointing out that I was going to fit mine in a slim, but still wanted to leave it looking like a lighter to the casual observer, he offered to donate a lighter for the purpose.
The donor lighter had been engraved, and one of the plastic panels was also cracked, so it had no place in his collection anymore. On getting the lighter, I removed the panels, and covered the engraving with a computer case badge.
The inner was measured to accept the USB dongle, before finally cutting the lower third off the inner itself. The removed section was slotted into the case with the idea that when the dongle section is in the case it rests against the lower third and keeps the cam mechanism in the right place, as well as preventing the dongle touching the case bottom.
The Flint tube was removed and Fibre optic strands were fitted in place of the wick. These being used to show when the USB dongle was accessing information. Finally a small collar was fitted on the inside of the inner (flush with the wick hole) to prevent the bonding glue used to hold the dongle in situ from fouling the LED near the Fibre optics.
Unfortunately, during the bonding process, I allowed the dongle to move a couple of degrees off centre. It is solely a visual letdown, but it was annoying to say the least. The finished project is ideal for me, and pretty much indestructible due to the Zippo case affording it decent protection.
I'm happy with it.