This paper model is Tree Fort, a "guard outpost" on the edge of the Candy Kingdom, as well as the home of Finn, Jake, Shelby, BMO, CMO, and Neptr, and where they can usually be found when they aren't adventuring, from the American animated television series Adventure Time, the papercraft is created by WebDude.
It was formerly owned by Marceline as revealed in "Evicted!." The fort includes a living room, a bedroom, a kitchen, a pond, a well, a bathroom, a chicken coop, an attic, a storage cave/garage, a secret place shown in "Dad's Dungeon" and a wide look-out view. After Flame Princess destroys the Ice Kingdom in "Frost & Fire," Ice King is temporarily moves into the Tree Fort in "Earth & Water," but leaves in "Play Date" after he reveals that the Ice Kingdom had been rebuilt for weeks. [Source: wikia]
You can download the papercraft template here: Adventure Time - Tree Fort Free Papercraft Download