This model comes from Dirk https://github.com/dherrendoerfer/uCNC_controller/tree/master/Extras/Plotter_v3 I just assembled on 3D space for clarity of those attempting to create one. Just complie, do not try to render (I have no control on source parts stls openscad, some of these are non-manifold). For the stl parts: clone repo and add on the same directory than this openscad file. Check his good work for the arduino controller and gcode sender! BOM (check Dirks repo Readme file) R/C servo for example this http://www.hobbyking.com/hobbyking/store/__662__HXT900_9g_1_6kg_12sec_Micro_Servo.html Openscad has parametric x,y dimensions: -assy(120,100); will give you a X of 110 mm and Y of 100 mm Watchit on Youtube: https://www.youtube.com/watch?v=kcXlak7RNV0