this is so cool. As a former electrical engineer (now I just write APIs) I really appreciate everything here and miss working with PCBs terribly! I don't have any ideas for what to make though, although it would be something along the lines of what you did.

I have an unrelated question. I was never very good at the physical hardware part of things (i.e. enclosures, plastic, etc), and I noticed for example in the video you appeared to be "sinking" a little screw nut into plastic. What is this process and how did you learn how to do it? If anyone can ELI5 because I'm a total newb at this.