What you will need
1. An Autodesk account so you can use their free web design software: Tinkercad
2. A free opensource program called Inkscape to generate the paths and create an SVG from the image.
3. Some Googlefu to find a black and white image of something you want to plot.
Let me just start by saying there is a myriad of ways to do this, this is just my preferred method. Inkscape can be replaced by photoshop illustrator for example, and you can replace Tinkercad completely if you use CURA as a slicer as this has the ability built-in.
So to start, let’s go find a cool image from google.
I usually just search for "black and white [insert subject matter here]" and find a cool picture like the one I've selected above.
Now, to save yourself going down the rabbit hole of "Pinterest boards" or "Tumbler" pages by going to the original site I’ve found google will just let you save the image from the search page. I’m not sure google actually gives you the best quality but that doesn’t really matter too much from my experience. Inkscape does some wonderful things when it converts it to a path. Just click on the image you want in google and download it by right clicking on it, in the black display box that pops up to the side, then "save image as". Done, now over to Inkscape.
First we need to import the image into our Inkscape canvas which after you’ve chosen it from your hard drive it will pop up the box as displayed below. I use the default settings but also render the image Smooth (optimizeQuality), which I couldn’t really tell you why apart from I just seem to get a cleaner image from this setting than any of the others. Once that’s imported, place it somewhere on the canvas and make sure it’s selected, you will see the black arrows around your photo as displayed in the 3rdpicture below. Then click the "Path" menu option in the menu bar, and select "Trace Bitmap..."
Displayed below is the window you will get to trace our picture to a bitmap. A bitmap is needed to create the paths that our SVG file will be comprised of. This is something that will be different for every file you use, depending on the amount of black and white you will need to use a different “Brightness cutoff” and sometimes if it’s a really good stencil/silhouette of something you may be better off using the “Edge detection” option. For the image I chose though, I went with the settings you see below. Just make sure to turn on “Live Preview” as it’s not on by default. The rest I left as default, but once you have your desired look then just click “OK” and close the window.
It will place the bitmap over your original photo, and this always confuses me so I move it to the left and delete the old photo (we won’t be needing that anyway now we have it traced). If you get completely lost and can't figure out which is which, double click one of them. The bitmap will show the paths as displayed below and your original image will just re-select itself.
Next, go to File in the top menu and save your SVG. It will default to the SVG filetype.
Next we need to go to TinkerCad and create a new design, or if your like me and have thousands of random designs you've built up after playing with TinkerCad for a while just "tinker" an old one and delete the previous model. Click the import button in the top right of the tinker space, select your newly created SVG file, and let Tinkercad do it's work and import it.
If you did everything right you will see an already extruded model that TinkerCad created from your SVG file. Rather handy no!?
Click the Export button in TinkerCad which is next to the import button, and make sure you have the settings as displayed below. We will want an .STL file for our preferred slicing software.
Once exported, open it in the slicer/program you've got setup for plotting and then slice it. I used S3D as detailed in my post here: Adventures in 2D plotting which gave me the output below.
That is literally it! Go print it and create some awesome sketches/plots. One thing to note here, because you're using offsets to correctly line up your pen to the bed the Gcode preview will show it slightly askew. Don’t worry about this too much, just line the model up on the bed where you’ve got the paper before you slice it and you should be golden. Just make sure to check the gcode preview isn’t off the edge of your bed otherwise your printer (especially Klipper/Octoprint here) will display an out of bounds error and cancel the print.