A thermally-conductive fluid ejector carriage device is used to dissipate heat from a thermal fluid ejector module in a fluid ejection device. The thermally-conductive fluid ejector carriage device is molded from a polymer, or a polymer material including at least one thermally-conductive filler material. The thermal fluid ejector module is brought into contact with the thermally-conducting polymer carriage to dissipate heat. The polymer can be a highly thermally-conductive polymer. A method of manufacturing the thermally-conductive polymer carriage includes molding the carriage at least partially from a polymer that includes thermally-conductive filler materials, and contacting the thermally-conducting polymer carriage with the fluid ejector module. A method for use of the thermally-conductive fluid ejector carriage device includes establishing a heat flow path from the fluid ejector module to ambient air through the thermally-conductive fluid ejector carriage device.