Abstract: Disclosed is a method for embossing a fold line onto a plastic sheet by first heating the plastic above its softening point and then embossing the material by passing it between a knurled flat roller and a cooperating embossing roller having a series of ridges suitable for embossing the fold line.

Abstract: Disclosed is an apparatus for making a substantially rigid plastic material having at least one fold line pattern with a series of generally parallel grooves, wherein preferably groove depth increases from the outside to the middle of the pattern. The apparatus includes a frame, a conveyor system for moving the plastic material along a linear path, a feeder situated at an upstream end of the conveyor system and adapted to position the plastic material on the conveyor system, a heater situated downstream of the feeder adapted to heat the area to be embossed with the fold line pattern to a temperature sufficient to form the fold line pattern, and an embosser having a knurled flat roller and a cooperating embossing roller having a series of ridges suitable for embossing the fold pattern.