I can't seem to select hull 003. ( the thicker part at the beginning of the corridor is hull003 )
Could this be related to what the active object is? I can't find what the active object means, nor if this is important or not. I see tutorials on how to switch but nobody explains why you would wanna do this.
Of course I googled this problem, and somebody was asked if he had used an modifyer. As you can see I used solidify.
It's driving me nuts, right clicking in the scene properties to select hull 003 does not seem to work either.