I think for the purposes of this one I’ll go with manually tracing it out with short straight segments drawn in OpenGL viewing mode.
The first time through there were several where the end vertices didn’t align, which meant the PCB outline wasn’t enclosed, but now I tracked down the culprits this is now sorted. With sufficient patience (and/or red wine) this manual process could be used for any complex shape, though after doing it I’m truly thankful most enclosures are squarish with radiused corners.
[quote=“cbernardo, post:10, topic:974”]
I tried using an ellipse in DXF but unfortunately that does not seem to be supported by KiCad. You can always ask for the ellipse feature to be supported. I also tried spline curves but they were ignored.
[/quote]There are discussions there about supporting importing complex dxf features, but they are quite old and don’t appear to have any recent active development. For the moment I think that’s a bit of a dead end for complex PCB shapes.
So my workflow was to create a footprint on the silkscreen layer to scale, place it in pcbnew, then to go OpenGL mode and place heaps of <1mm line segments on the Edge.Cuts layer. Then back to default view and delete the footprint. Then outside KiCad deleting the footprint’s .kicad_mod file to clean up.
I’m very much looking forward to seeing how this board turns out. Thanks everyone.