a process for forming a specific length of extruded thermoplastics material trim strip for automobiles includes the step of extruding the strip directly onto an endless carrier belt moving at a speed matching the emergence speed of the extrudate . the extrudate , therefore , is less subject to stresses causing unpredictable length changes on cooling . it is therefore possible to predetermine the cooled , matured , final lengths of strip and to provide moulded end portions on - line .