Why don´t certain shapes/faces extrude? So i am working on a project, where i created a shape based on an image, but when i extrude it certain areas just won´t extrude right. As you see in the screenshot there are no "walls" at some places.
 Why is that? I guess that i used a couple techniques in the process to create vertecies, that apparently don´t work well together.On the other hand i don´t see why this should be a thing. Is there a way to assimilate the condition of the whole mesh so it extrudes normaly?
Removing doubles may fix it in this case, but similar results may show with wonky normals, generally fixed by Ctrl+n in Edit mode