spaces 34 are filled with corresponding inserts 36 preferably rigid foam insulation such as rigid polystyrene the thickness of each insert 36 is selected to match the height of dividers 31 and peripheral wall 31 a in practice the top wall 32 of the frame portion 30 can be attached or molded to the remainder of the frame portion after installation of inserts 36 followed by attachment of a corresponding half of the comfort pad 14 to the top wall of the finished frame portion the foot members 16 are conveniently made of the same material as the frame portion so that the foot members 16 and the frame portion bottom wall peripheral walls 31 a and dividers 31 can be formed as a single molding fig4 a and 4b are diagrammatic top plan and side views respectively of the illustrative embodiment of the invention sectional views a and b represent cross sections through the support base at the positions indicated in fig4 a view 4 c illustrates a hinge connector 26 which connects the two halves 12 a 12 b of the foldable support base 12 together and having the u shaped support members 24 of hood 20 pivotally mounted thereon the hinge connector 26 may be of any design suitable for attachment to the two halves.