I'm currently modeling a plane where the exterior was modeled first and the interior was added in with Ctrl + J as a separate object, so the plane as a whole is non manifold.
Here's the interior of the first class room:
This is in-between the interior and exterior (not connected):
So, as you can imagine, I'm trying to cut a porthole into the plane with the porthole object. This is the boolean modifier on the plane (raising the modifier any higher deforms the plane):
Rather than getting a nice clean cut, I got this:
The interior part was cut through, but not the exterior. I find this extremely confusing, because it should have worked in theory. This is what the wireframe looked like before the modifier was applied:
In the image, the porthole object was selected, so in the plane mesh you could see 2 definite cuts. So how can I get it perfectly, just like the wireframe "preview"?
I thank you in advance for helping.