Below is a list of Corrugated Boxes manufacturers from Belvidere, Illinois. Corrugated boxes are storage and shipping containers that are constructed of corrugated materials. A corrugated material is rippled, fluted or ridged sheet, and corrugated containers are usually composed of a corrugated sheet sandwiched between layers of flat sheets. Container materials are often corrugated because of the added strength that the process gives to materials without adding significant weight.