Abstract: An apparatus suitable for extruding curable polymers for forming elastomer articles using additive manufacturing, and curable fluorine-containing polymer compositions suitable for use in such an apparatus are disclosed along with an additive manufacturing method for forming a fluorine-containing elastomer article including providing a filament formed of a curable fluoropolymer composition; providing an additive manufacturing printer having a drive mechanism and a printer nozzle; feeding the filament into an additive manufacturing printer through the drive mechanism and through a longitudinal passage defined by an interior wall of a support tube, wherein the support tube extends from a first end to a second end, and wherein the second end of the support tube is positioned near an inlet to a printer nozzle; applying heat to the filament; and printing successive layers of the heated filament exiting an outlet of the nozzle onto a substrate using the additive manufacturing printer to form the fluorine-containing