Thank you for the code and tests!

Figure.UnimeshInfo()

In your MorphTools, it looks like I could extend it with the few things I need.

Using the unimesh geom, I can check for symmetry & create the mirror map, get the deltas for a specific source morph, create the new morph in the appropriate actor(s), write the deltas using the mirror:unimesh map and the actor.geom map(s), then create the master in the body.

critically asserting that unimesh is symmetric about x=0.

Feel like I'm missing something. time to test and see what explodes :D