Dave Rowntree and I chatted a bit at Supercon and he ended up writing a nice article for Hackaday on the machine. Thanks Dave!

https://hackaday.com/2024/11/06/rapid-prototyping-pcbs-with-the-circuit-graver/

One of the great things about seeing your project get a bit of press is that it can get enough coverage that interesting people with relevant experience chime in. That seems to have happened here! A commenter named Shara linked to a few pictures which used a used drag knife to carve up a bit of copper-clad substrate, and it looks like they got great results: 

https://imgur.com/a/RwRdv00

Copying the photos here in case the imgur link dies; as suggested above, these aren't my photos:

Shara! Whoever you are, please send a link to your project so I can include it here. These tests look like thin FR1; it seems you might have had the same challenges I had with entry/exit points shorting, but got it to work in the end with hand touch-ups or maybe toolpathing improvements. I'd love to learn more about your setup and see a video of it in action! What feature size can you hit? How fast? Does the cutter get dull quickly? What kind of machine is it driven by?