Hi.... I wanted to fetch some ideas to add to my cnc pen plotter with grbl. I followed this guide diymachines.co.uk/arduino-cnc-drawing-machine.
And that led to what?
Hardware or software ideas? What about being able to change pens under CNC control?
So, I made the machine and now i want make some additions to it. Could be any, hardware or software
I am trying to implement this. https://howtomechatronics.com/projects/diy-pen-plotter-with-automatic-tool-changer-cnc-drawing-machine/ Taking some inspiration from this design 
If even you don't know what you want it to do, I ask you, how the hell are we supposed to help you?
I'm just asking for suggestions, not help!
They seem to come from the same source, don’t they? You need help with trying to keep busy!