forming {HEAD ~ a first, continuous region} of {TAIL ~ the wall} and at least one, second, smaller region on the first region of PVC materials which integrally merge with each other in the step of forming the regions on each other where the regions are on each other, the PVC material for the second region being more crosslinkable by irradiation than that for the first region for greater hardness; and 
of
forming { HEAD ~ a first , continuous region } of { TAIL ~ the wall } and at least one , second , smaller region on the first region of PVC materials which integrally merge with each other in the step of forming the regions on each other where the regions are on each other , the PVC material for the second region being more crosslinkable by irradiation than that for the first region for greater hardness ; and
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH