This is primarily for crane style 3D printer. this design is to get the extruder as close as possible to hotend and get all the benefit of direct drive but still can move fast because the weight of the motor is offset by second arm. this only require 1 X axis motor to be located on the arm of the one carrying hotend. the second arm is not necessary to be belted. Required: - Various Openbuilds parts / wheel / and plates - Bontech BMG