Collapsible and reusable container insulator

An insulator for a generally cylindrical liquid container, the insulator comprising a pair of joined collapsible side walls expandable into a cylindrical sleeve, the side walls being joined by insulating strips having an insulating foam in the gap between the insulating strip and the side walls, the side walls having a lower periphery into which an insulating bottom is removably insertable and fittable, the side walls having an openable insulating top lid attachable to the side walls and openable to provide access through the insulator to the contents of the container, the top lid being attachable to the side walls by a tape hinge enabling opening and closing of the top lid on the side walls, the insulating bottom being constructed of a soft material to prevent scratching of a table surface on which the insulator is restable, the side walls, insulating bottom and insulating top lid being constructed of a material having insulating properties to minimize transfer of heat therethrough and to minimize the warming effect on said contents by incident solar radiation, the collapsible side walls having a springiness or tendency to collapse when assembled, whereby axial gripping force is exerted on the insulating bottom to retain the insulating bottom by friction, the insulating bottom being provided with three circumferential ridges including a lowermost, middle, and uppermost ridge, the middle ridge being undercut to provide a snap fit with said side walls, the side walls having a lower gripping kerf for receiving the middle ridge.