Abstract: A disposable container is made from an integral blank of corrugated cardboard for folding between a relatively flat configuration for storage and a set-up configuration for receiving articles. A bottom wall is foldably attached to two pairs of side walls. The side walls are joined by four pleated walls to form a seamless interior portion when the walls are raised into a set-up configuration perpendicular to the bottom wall. The side and pleated walls include user-friendly self-locking elements for securing the set-up configuration. A moisture barrier coating on the interior permits ice and perishables to be received in the seamless interior portion to provide a disposable insulated cooler. A pair of folding top walls provide handles. One of the top walls includes a locking panel with lateral locking tabs which fold down across the top of the set-up cooler so that the closure locking tabs are seated in respective planar slots formed by the raised walls for positively closing the cooler interior.