Ideas for "Little Big Planet" costumes basically focus on making a generic sack person attire and customizing it with items from the game. The sack person's head can be built around a bike helmet or top hat and filled with foam. The body can be made of burlap and felt.
For the head, build it up with foam, carve it into the right shape and make an opening for the mouth. The eyes can be black round buttons or black felt. Cut the burlap according to the body measurements of the wearer and sew the front and back pieces together with shoe string. The front body zipper can be crafted out of grey felt, foam or thin silver sheets. Customize the sack person costume with a cape, scarf or other accessories that can be found or downloaded in the game.