offset closed brep (shell surface?)

I am trying to create a set of 3d voronoi cells that are offset from each other by a specific distance.  scaling by the center of volume creates gaps that are proportionate to the edge distance from the center point which does not work for this application.  I have tried using the voronoi intersection with the bounding shape and then offsetting those curves on the surface of that shape but that causes large sweeping arcs to appear on some of the cells as some of the smaller cell walls become inverted(I believe) during the offset operation.  I have also tried to use the surface offset operation with similar failings due to the same reason. I have been able to create a successful offset with the weaverbird offset mesh component but then fail at converting the mesh back into a closed brep after the offset so I can boolean the offset shape creating my final profile.  is there a way to combine planar mesh polys into single surfaces? or is there a way to offset a closed brep inside it's own volume?