Abstract: A fused filament fabrication system and method comprises a motor for moving the system along a linear rail during operation, a drive gear coupled to the motor. The drive gear rotates in the direction of the motor during operation and selectively operatively engages first or second idler gears during operation of the system. The system also comprises first and second filaments for the selective passage of material to corresponding first and second extruders, the first filament is positioned between the first idler gear shaft and idler bearing and the second filament is positioned between the second idler gear shaft and idler bearing.