The kotak is a large wooden chest with a removable lid, which forms a tray on its own. All the wayang puppets are kept in this chest, together with other equipment such us the screen. To store a complete set of puppets, the chest should be about 1.5 meters, 75 centimeters wide and about 60 centimeters deep with the lid on. To keep the wayang puppets flat and to prevent their movable arm becoming entangled, the puppets are often put first, about thirty at a time, into large portfolios, or placed between two sheets of thick card strung together.

During a performance, the lid is taken off the chest and placed on the dalang’s right, where it acts as a shallow tray for puppets awaiting their turn to appear “on stage”. The opened chest is placed close to the dalang on his left-hand side. Even though most puppets have been lined up on either side of the “stage”, standing in the banana boles, the chest contains still more puppets. The chest also act as a sound-box for the knocking and rattling sound made by the chempala and kepyak.