Bowden dual/quad extrusion extruder (single-nozzle single-drive) + video

623 623zz 624 624zz arduino due Arduino Mega bowden extruder dual dualextrusion dualstruder dualstrusion dual color dual extruder dual extruders dual extrusion dual material E3D e3dv6 E3D Hotend E3D v6 extruder kossel kossel 2020 kossel mini makerbot mini kossel MK8 mk8 extruder NEMA nema17 NEMA 17 prometheus Prometheus V2 prusa prusa i3 prusa i3 hephestos prusa i3 rework Prusa i3 Steel ramps RAMPS14 ramps 14 ramps fd ultimaker