In a scene I’m working on, I just plain create a cube/cylinder, delete the top face and then extrude those vertices around in 3d space and then subsurf it and this is how it turns out. The error, however, occurs before the subsurf, so if I remove the subsurf, the faces still look strange.
I have tried recalculating normals outside, turning doublesided on/off, and here comes the strange thing: I also tried creating a similiar mesh in another (blank) blender project and that one did not turn out like this.
If someone could pinpoint the mistake that would be great! Thanks in advance.
EDIT: Oh, and it also does not occur when only extruded along two axes, but when I start moving those “vertex rings” that makes up the cylinder joints around in the third axis this happens.