PURPOSE: To provide a low-cost mold piece for polyethylene terephthalic resin twin- screw drawn blow molding of bin by extrusion blow molding of preforming piece.

CONSTITUTION: Parison P1 is formed by extruding melting resin at sufficiently low temperature from a dies head 1 having an extruder 2,3 ... that extrude melting and differently colored polyethyrene resin. When the parison P1 attains a pre-determined length, a piece metal mold 5,5 bit and cut it off by chipping 4. A piece head molding nozzle 6 penetrates the parison discharging the pressurized fluid from its nozzle tip. The streched piece P2 to the radial direction is fitted with a core mold tool 7 having a drawing rod 8 that are heated up to a drawing blow molding temperature and attached to a blow metal mold 9. Pressurized fluid is casted to form a twin- screw drawn blow molding.