So as I am creating simple lines in this case with the polygon tool, I figured out I can actually just trace back over the line and then its fine.
Clearly this won’t work with imports, but thats ok for this project.
Traffolyte is a hard plastic bonded in 2 colours (normally 3 layers, like White, Black, White), you remove the top colour to reveal the middle one. I’ts used a lot in electrical switch panel labels etc.
It comes in various names, so you may well know it as something else, here is a picture :
I have been playing a bit to work out speeds and what not. I found the double reverse pass works well because I was engraving text with a single line font that reverses itself to be a closed font that behaves correctly.
It might well be that I find a good spindle / feed rate that works well with a single pass.