I created some models in c4d (with splines and the loft function) and they look fine there but when I import them into unity the back part is not visible baked or not. Its only visible from certain angles. I know people sometimes do this on purpose but idk how it happened. Sorry for the noob questions and bad pics.
That looks like a backface culling. Polygons have no thickness, so to let the Renderer know which side is the front each polygon, there is something called a normal. To get those faces to render you would have to use a shader/material that double sided… Err, I forget the technical term… If there is one, sorry… The other option is polygons facing the other way too. So instead of a plane as a wall, use a cube. But if nobody is going to be able to see the back of these props… Or the example above, we the walls. There is no need to worry about double sided materials or more polygons. What you’re seeing is normal. So, really it depends on how you’re using the prop.