This papercraft is the Skeleton Key, based on the game The Elder Scrolls V: Skyrim, the paper model is created by Brokensoul. The Skeleton Key is an unbreakable lockpick found in The Elder Scrolls V: Skyrim. This artifact is attributed to the Daedric Prince Nocturnal. It can be obtained from Mercer Frey at the end of the Thieves Guild quest "Blindsighted". In order to complete the remaining quests for the Guild, the Skeleton Key must be returned in the Twilight Sepulcher.
The Skeleton Key can be used like a regular lockpick and can be kept indefinitely, provided it's never returned to the Twilight Sepulcher. In addition, the Lockpicking skill will still increase when a lock is opened. Keeping the key effectively renders the lockpicking perk Unbreakable entirely obsolete, as well as most of that skill tree.
About the paper craft:
You can download the game paper model here: The Elder Scrolls V: Skyrim - Skeleton Key Free Paper Craft Download