Abstract: A safe having an outer shell mainly of plastic material, an inner liner of metal, and a filling of heat-resistive material between the shell and the liner. The safe body has a separate cover or door across the top of the body, and when the door is removed, it allows unhampered access to the complete area of the liner, which constitutes the storage space for the articles to be protected. Both in the safe body and the separate door, the filling material is put in while in a flowable condition, and filling is stopped when the space is not quite full. The panel members which are then put in place to close the filling openings have projections which make contact with the filling material to give stability and firmness to the panel members even though large areas of the panel members may not be in contact with the filling material. A simple latch and key mechanism is also disclosed.