But next time around for something similar probably try to make the pieces push through each other a little bit instead of having them kind of skimming right along each other. Either that or try to get the exact same surface in the areas that are coincident instead of having one rotated or fragmented differently than the other.

Having them push through a bit tends to be easiest, since it then doesn't make too much difference exactly how the bottom pieces are structured since they will get sliced off anyway.

- Michael