PDF cartoons of disk formation:
Disk formation by classical infall : classical infall schematic
Disk formation by concentrated infall: concentrated infall schematic
How do I make these illustrations?
These illustrations are made digitally. I use the Autodesk Sketchbook app. It’s free and available on both android and ios. I use an apple pencil on my ipad, which is not required to use the app but I find very useful as a person whose (limited) art training has been with pencil on paper. The app allows me to upload images directly to google drive, it’s pretty convenient.
If you’re interested in making your own schematics, I would recommend a basic workflow that uses layers to create separate elements of your image. Play around with different brushes and their settings (size, opacity) to create different effects and control their strength in the layer settings.