Here's a bit to show you how this kind of shelling is kind of more complex than it first seems.

Here is the result of doing a separate and then offset of your shape to the outside:





When separating objects into individual surfaces like this each surface will be offset individually and there won't be any attempt to deal with extensions. But this way you can see how the sort of basic shape that each surface wants to have for its offset, and notice there how since each surface is at a different angle to one another that there is a different amount of space between the "natural offsets" ? That's the kind of thing that MoI's geometry library will not handle currently, it means that there will be a change in vertex/edge structure in those areas if they were extended and intersected with one another properly.

- Michael