This simple mod converts a 3d printer into a pen plotter. I have tried to take the simple and quick approach when it came to creating this. This replaces the part cooling fan so that you only have to remove the fan rather then the whole extruder assembly. Taking the simple approach does have some downsides. First one is that this pen is offset from the extruder and has to be taken into account when setting up an image to be printed. Secondly you need to have good bed leveling abilities, this is not a spring loaded setup so the pen needs a level bed.
I included two files for downloading. One works on my wanhao v2 and the other is for v2.1 printers. I however don't own one and just went off of what a friend told me, so hopefully it fits.
You can check out this video of the mod in use. https://www.youtube.com/watch?v=eHzM3ZcmNuc