The actual extrusion of the mid-plane into two parallel surfaces is a no brainer in Python. In most cases of course wasting polygon on the inside makes no sense. The issue is with finding edges and in that distiguisning real edge hems from internal modeling artefacts. There has been some discussion about such tool in the Python forum a few years ago.

Centerplane geometry garment models exported from Marvelous Designer can have the vertices of the pattern edges in a metafile. It would be doable to define rounded edges from that information, either as geometry or as displacement map. I never pursued this course of action myself because MD can export 'thick' geometry models with rounded edges and correct stacking of plies, and that serves me.