Attached is a macro for partially mirroring 3d sketches.
It's currently limited to mirroring sketch points and line segments. (It is mirroring about the yz plane, and with a slight offset, but that could be changed.)
Putting several initial points onto any circle or arc or splines ahead of time would allow the ability to recreate those entities on the mirrored side by hand after the fact. Trying to create those in the macro I don't think is possible, because of the idea that there could be multiple solutions for those arcs, circles etc.
One question I have:
Given the example file, and running the macro, what is the point on the left above the circle center, the one that appears to make no sense.