Adafruit’s most recent Part Finder Friday column featured these cool no-nonsense BUD USB 7201-C polycarbonate USB dongle cases, available at Digi-Key and Mouser and probably other places. They cost about $2 apiece if you’re only buying a couple and come in three pieces—two snap-together clamshell halves plus a connector cap—and take a 19x45mm circuit board, which seems to be a pretty common PCB size among commercial USB keys. I just ordered two to re-skin some generic thumb drives I own with bulky cases that won’t fit into the back port of my Xbox 360. Good find, guys!
Clear Snap-Together USB Project Enclosures