Blizzard BattleNet (digipass) authenticator.

thingiverse

People often use this thing as a placeholder for the authenticator device that Blizzard Software requires for World of Warcraft and other BattleNet games. Instead of making something directly useful, its purpose is to provide a basis for items like skins and cases to fit onto an actual authenticator. The idea behind creating this thing was primarily to enable the hearthstone authenticator box seen in certain remixes. Still, users can definitely come up with their own ideas, too.