I did what Michael mentioned in his second reply and Separated the surfaces, I then Shelled them (Direction = Flip) and finally Boolean Unioned them.

There are a couple of problems at the front that might be editable, but overall it's not too bad from what I can see.


Martin.

Thanks blowlamp for the tip. That will make it quicker and easier. I never considered that option so glad you suggested it.

In this case I don't need perfect surfaces on the interior so a couple of bad joins here and there won't matter.