The 2nd extruders output just sits on top of the 1st extruders. Thus any X-Y misalignment will not break anything. You can measure the position of the red squres against the gray cross with digital calipers (they stik up just enough).Prints with two extruders. The 2nd extruders output just sits on top of the 1st extruders. Thus any X-Y misalignment will not break anything. You can measure the position of the red squres against the gray cross with digital calipers (they stik up just enough). Then you know how much to enter in the X.Y offset of your 2nd extruder to get perfect alignment. The two STL files are the Left and right extruder. The openscad fil - just enter L, R or B in the first parameter to view Left, Right or both views.