The problem with an enclosure is that it limits your access to the pins. I'm using the mounting holes to mount it to the deck of my bot with standoffs (2-56 x 3/16 lg.).
If it ever becomes a dedicated "programmer" (programming ATMega168s for Boarduinos or Bare Bones Boards) then I may try the altoids tin. With stick-on rubber feet, of course. Until then it needs to be in the open, for trying out new sensors, etc.