thick - skinned extruded metal honeycomb structures , and a method and apparatus for making them , are disclosed wherein a plasticized powder metal extrusion batch is extruded though a die assembly comprising a die and annular mask , the mask having a central outlet for extrusion of the skin and honeycomb core and an extrudate reservoir adjacent the central outlet , the die and mask cooperating to form a skinforming gap fed by the die and by the extrudate reservoir , such that batch material supplied from the reservoir and directly from the die combines to form a thickened outer skin which is integral with , and resistant to separation from , the honeycomb core .