Have a few old DVD drives collecting dust? Create an Arduino-based CNC plotter with them.
Although they might have been amazing technology in 1993 or so, CD drives, and later DVD drives, seem to be used less and less these days. If you have (or can source) two of these drives lying around, perhaps you can build a plotter out of them.
Of course, that’s easier said than done, but Michalis Vasilakis’ excellent tutorial should give you a good path to either follow or expand upon. The project features a clean-looking plexiglass frame with two stepper motors to control X and Y movement, and a servo for Z-axis control. It can work with whatever pen or pencil you have handy.
The Maker’s tutorial includes both a parts list for beginners, using an Arduino Uno to simplify things, and an advanced list, where an ATmega328 is employed with a larger number of components. It goes into how to disassemble the optical disk drives, and how to determine what each wire going into the stepper motors does. Finally, the instructions go over how to program the machine to actually draw what you need using Inkscape as the image source.
What’s more, the plotter can be equipped with a Bluetooth module for wireless printing of text (or images).
If it can use a pen, then one would think it could also use a rotary cutting tool for light engraving, but according to the writeup, attempts at this were not successful. On the other hand, this “e-waste 3D printer” uses many of the same materials, so that design might give you more ideas if a simple pen mark isn’t suitable for your purposes.