Planning to build a string plotter, but using GT2 timing belts instead of strings, and instead of spooling up excess, letting it slack down below the plotter head. All electronics go in the plotter head, making storage in a small box possible. I'm basing mine roughly on
https://www.hackster.io/fredrikstridsman/stringent-the-15-wall-plotter-d965ca in hardware, but more closely in firmware.
The best thing about the Stringent firmware base is that it doesn't need a Gcode file, it just takes a non-bezier SVG (all straight line segments) on a micro SD card.
I was originally going to use an Arduino Uno clone that I have laying around, but then I found my Adafruit Metro M4 (same physical footprint, 3.3V logic, and holy mother of shits it's 32 bits and can be clocked to 200MHz!)... only to find that the Metro M4 is incompatible with my SD/touchscreen stack. So I went with my trusty workhorse, the Arduino Due, which only runs 80MHz, but it's plenty to overcome the need for a super-lightweight ASCII-to-float routine, and to compensate for me using much smaller pulleys. All I have left to do for software while I wait for some hardware to arrive is figure out how to replace the shitstorm of a text parser with an atof function version. The other nice thing about the Due is the plethora of pins available, which means there's always room for more features, and I can actually run everything on digital pins rather than needing to run several digital functions on analog pins.
The UI is pretty simple and has just a static screen image, which takes about a second to draw. But touchscreen operation should be nice, especially with this good capacitive panel.
CAD is pretty minimal, I'm planning to print the part with the wheels and then use a piece of plywood to mount everything else. You'll notice there's an Uno clone on there, uh, that's supposed to be a Due with a touchscreen stack. Whatever, it's going on a piece of plywood, mounting won't be a problem
All this because I don't have money or space for a needle cutter. And I'm still wondering how precise it is.
Now, for the question: Is it worth running this off a 3S or 4S and a big UBEC, or should I test my luck and run it off a power supply? Also where can I find a good ballpoint pen that can slide into a 3mm hole?