Rectangular parallelepipedic case and method of producing the same

摘要

A rectangular parallelepipedic case includes four or more walls formed by bending a single plate. To produce the case, a double plate is used. The double plate is formed from plastic by extrusion, and first and second plate elements confronted with each other. Partition portions interconnect the first and second plate elements, and extend in the direction of the extrusion, to define plural hollow chambers between the first and second plate elements. The double plate is bent along bend lines substantially at a right angle. At least one of the bend lines is at least partially curved.