Also it can be a lot more difficult for offset to process a whole bunch of joined surfaces like it looks like you have in that case.

It will go through a process where it tries to extend and intersect all the offset pieces with one another, and if those pieces just kind of barely graze one another that can make for a kind of wiggly and badly defined intersection curve which will give bad results.

You may need to do something like offset only a few key surfaces, and kind of construct some inner pieces hanging off of those to build the interior wall.

- Michael