Container with inflatable, floating liner of uniform thickness

A container with internal cushioning, comprising:

• a casing having side, top, and bottom walls which define a storage compartment, said casing having a closeable opening,
• lining means consisting of an inner liner covering the entire inside of said opening and attached to said casing over the entire periphery of said opening except for one edge so as to form a slot for access to the space between said casing and said liner,
• securement means for attaching said liner to the inner surface of said casing at a plurality of places,
• a removable inflatable envelope made of two sheets of an air-impermeable material having a pattern in conformity with the inner surfaces of said casing and forming a hermetically-sealable cavity, said envelope being sized for insertion, via said slot, into said space between said casing and said liner, said two sheets of said envelope being sealed together at their edges, said envelope being positioned in said space between said casing and said liner, said envelope being held in position by said liner,
• captivating means for closing said slot after said envelope has been inserted into said space,
• inflation means for inflating said envelope once it has been inserted into said space, and
• restraining means for maintaining said sheets of said envelope in parallel relationship when said envelope is in an inflated state, said restraining means comprising a plurality of attachment points which join said sheets together at a plurality of spaced locations thereon, an area on each of said sheets surrounding each attachment point being separable from the corresponding area of the other sheet so that said sheets will be spaced apart with maximal uniformity when said envelope is inflated.