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The Tablet Pieces are three scraps found in Paper Mario: Sticker Star. Mario is required to retrieve them all in different locations: one is in an underground room in Drybake Desert which can be accessed by a sand flow not long before the Comet Piece, one is in Yoshi Sphinx at the end of the sphinx's tongue, and one is in Damp Oasis inside the closet of the changing room.
Once all three Tablet Pieces are obtained, they must be placed onto the empty space in Drybake Stadium, turning it into the stadium itself.