externint16_tflow_percentage[EXTRUDERS];// Extrusion factor for each extruder
externfloatfilament_size[EXTRUDERS];// cross-sectional area of filament (in millimeters), typically around 1.75 or 2.85, 0 disables the volumetric calculations for the extruder.
externfloatvolumetric_multiplier[EXTRUDERS];// reciprocal of cross-sectional area of filament (in square millimeters), stored this way to reduce computational burden in planner