The folowing B.O.M. is suitable for mounting the extruder to a Prusa i3 X-carriage. (2) Idlers (Printed) (2) Bodies (Printed, One mirrored before printing) (1) NEMA 17 Stepper with M5 shaft (1) 608 Skate Bearing (2) M3x25 Screws (2) M3x45 Screws (or M3x40?) (1) QU-BD Drive Gear (10.5mm Hobb Diameter), or similar