[pwagland]

An interesting article, however my question is technical.

In the "The Mechanism of Extraction" section, how is that image made? It is nicely laid out, and has a nice "hand-drawn" feel. This is a good format for many technical drawings, but I have not found any tools that could create this.

[LandR]

Looks a bit like excalidraw. It's not, but it's pretty similar in look.

https://excalidraw.com/

[frutiger]

Excalidraw