A spring loaded pen holder to attach to an extruder base.I designed this so I could play about with plotting without taking the extruder off, not ideal but thought it may be of some interest. The pen is secured by the clamp and the whole assembly screwed to the extruder base. The pen is then positioned so it is touching the printing plate and the Z end-stop adjusted accordingly. See comments below for software to drive it. Build Instructions. Print the two parts. Saw out the supporting struts and maybe tidy up so the two halves slide together nicely, add an elastic band to spring load the action. Add a nut and bolt for the pen clamp, and self tapping screw to fix the holder to the extruder base.