A method of forming an extruded honeycomb structure having a matrix of straight cell walls defining a plurality of straight cells running generally parallel to the axis of extrusion, and a matrix of {HEAD ~ cross} {TAIL ~ directional or corrugated cell walls} defining a plurality of cross directional cells running generally perpendicular to the direction of the straight cells, by: 
A method of forming an extruded honeycomb structure having a matrix of straight cell walls defining a plurality of straight cells running generally parallel to the axis of extrusion , and a matrix of { HEAD ~ cross } { TAIL ~ directional or corrugated cell walls } defining a plurality of cross directional cells running generally perpendicular to the direction of the straight cells , by :
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