What is the workflow here?

I’m found a workflow saved file and this is the thing I was looking for the learn. How do the person turned the rough shape into the smoothed one?
workflow.3dm (222.7 KB)

I don’t see a direct connection between the models to point you towards one command specifically. If the models represent a sequence of steps, it looks like the top surface was extracted and rebuilt or deleted with a new surface being made as a Sweep2.

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