So the stupid thing is that Cybermotion doesn't display all the lines by default, just the most important ones (so obviously you see a cube in stead of a cube with a line on each side). So I turned those extra lines on, and guess what? There it was.
So I imported the actual shell into the file of my home for comparison. I figured out a while ago that two stories of my home should be about as high as the doorway to the shell to get the right proportions. I wanted to check this in-game though, so I imported back to Blender, but it asked me for a Size Constraint. What is this and what should I do with it? I just took the default number and now trying to figure out how to prepare it for Uru (after not having done that for a quite a while).
Anyways, here's the reason I needed another shell:
Here's what it looks like in 1 shell:

So that looks kinda okay, doesn't it?
Well no, because I want there to be lots more in it. Here's a quick something I did:

ph34r teh Paint skillz! :ph34r:
Although most things that picture are not really to scale, it's pretty obvious that it wouldn't all fit into one shell... I think. And I'll come up with more things to put in there for sure
