a polymer molding system and method of operation produces synthetic article of manufacture that simulate natural building materials such as wooden shakes and stone roofing tiles . the system preferably feeds at least two dye compounds and a polymer filler material into an extruder for heating into a ribbon . the ribbon is heated as it travels through the extruder and through an outlet end where a slicing unit cuts the ribbon into a plurality of preforms at a pre - defined rate . because the dye compounds are not homogeneously mixed with one another , the ribbon and hence the preforms are generally of at least two colors . each preform is individually fed into a press that stamps and partially cools the preform into the simulated article of manufacture shape that also accentuates the varying colors . preferably , the stamped article is then flexed or cupped between a carriage and a dead weight prior to crystallization and where it then cools and crystallizes to a final shape . this cupped shape of the article of manufacture is generally straightened out under stress when the article is installed .