Change the 3D printer to a 2D plotter or handwriting machine is not a new topic. There are a lot of videos explained how to do it. But even it is said to free or easy after I watched the video I think there are still some issues that must be considered. Most of them use a ballpen as a writing tool but with hard contact with the 3D printer bed. It is hard to adjust the height of the ballpen or it will harm the bed or not contact with the bed. I use a flexible ballpen with a spring inside to solve the problem. Another issue is they usually remove the hot-end when used as 2d writing tool. It is also not convenient since I don't want to disconnect the hot-end at any time. It can be solved by adjusting the g code file before printing. Since the hardware is established. This handwriting machine is easy to change to a 2D plotter when you modify the g code file. This is the next video topic.
I also attached the f3d file. You can modify it to fit your 3D printer.

https://youtu.be/teIbdi_H64g