a process for coextrusion blowmolding of multilayer polymer articles , wherein a multilayer parison is extruded through a die , introduced into a mold , and blowmolded , the flow of multilayer plastic material being periodically interrupted , and additional plastic material being injected into the extrusion die at timed intervals , so that this additional material forms portion of the parison which later are trimmed from the molded article and reprocessed for reuse .