how to divide the grain into two parts according personal need

[USTChd]

Dear all,
I have obtained a 2D polycrystalline model with Voronoi tessellations. And then I want to divide each grain into two parts: a thin ring along the grain boundary and the rest part of the grain. But I don't know what should do even if reading the manual. Could give me any suggestions on it? Thanks a lot.
Dong

[rquey]

This is not possible at the moment, see related discussions.