Plotters and drag knives

Upgrading the 3018 to be able to make precise drawings or cut vinyl, cardboard, and paper mechanically is the least complicated modification you can make to your 3018. For the most part, you are replacing the spindle (temporarily) with something to hold a pen/sharpie or a blade. The rest is controlled by the software and G-code. Consider: If you have no traversal in Z other than to raise or lower the toolhead, your drawing is rendered entirely in 2D (no depth to worry about), so it is reasonable to think that your 3018 can draw and cut using the same software. You would just have to work on the process of raising and lowering the toolhead where appropriate.

While these modifications are certainly simple enough and absolutely reversible, you should know that the machine will appear to operate slowly. This is because the 3018s use leadscrews in all axes and those are meant to move a heavy toolhead at a reasonable rate for cutting. In the case of these upgrades...