Modificated scripts from the original plotterfun: https://github.com/mitxela/plotterfun
Instead of drawing squiggles, the pen width will be modified.
In GRBL-Plotter the pen-width can be translated to a Z or S value to change the hight / contact pressure of a paint brush, using the z-axis or a RC-Servo.
Try it out here: https://grbl-plotter.de/plotterfun-width/
Check also https://grbl-plotter.de/plotterfun-color/ to get RGB or CMYK squiggles.