Hi.
I'm not sure about the dxf part, but the svg could be way cleaner.
Hmm how was that
tutorial...
From 8.)
- once you have the paths with the black strokes, add the same stroke style to the square at the bottom
-select one of the black outlines, press Ctrl+C, then select the square and press Ctrl+Shift+V- - select all 9 paths and combine them together (Ctrl+K)
- convert strokes to paths (Ctrl+Alt+C)
This should result in a quite good path you can work with.
Only flaws are the unnecessary nodes at miters, but those don't show up in the cutting as per se.
For the cutting, maybe this path can be broken apart (Shift+Ctrl+K), and the subpath's z-order changed.
(After breaking apart add a stroke and no fill to the paths; to change the Z-order PgUp, PgDown, Home, End can be used -in practice, select the objects in the preferred order and press End every time a new one is selected.)