I just recently started using Blender, so I am new to this.

Currently I'm working on a model of a mask. For that I created a flat rectangular shaped block, where I'm trying to cut out eye holes using the boolean modifier and a cylinder.

After applying the boolean modifier I fixed the ngons and removed doubles. Now I get the unwanted result of a face overlapping the edges of my mesh:

Mesh View

As you can see the marked area creates an overlapping face. In the render it will look like a rotated square:

Render Preview

I appreciate all the help.

  • $\begingroup$ Concave polygons can cause artifacts. Could you explain your topology necessities for this project? $\endgroup$
    – Carlo
    Aug 24, 2018 at 15:11
  • $\begingroup$ Well the at the end it should simply be a wooden mask with two eye holes carved into it. The project is just for learning purpose. $\endgroup$
    – josias
    Aug 25, 2018 at 4:41
  • 1
    $\begingroup$ What you are seeing is explained in answers to this question $\endgroup$
    – sambler
    Aug 25, 2018 at 9:52

1 Answer 1


As previously said by Carlo: "Concave polygons can cause artifacts" because Blender is not sure how he is supposed to fill the surface between the vertices.

So here is a better way to make a hole in a 4x4 surface. I think you should avoid Booleans as much as possible, especially for such a simple operation. To make a hole you can simply select the central point and delete it. Then to round the shape, select the edge loop and use the LoopTools addon > Circle. Then you can extrude once, then scale down the extrusion, give it the shape you want, etc...

enter image description here

  • 1
    $\begingroup$ Would be good if you could add some information as to why their current method isn't working. $\endgroup$ Aug 24, 2018 at 16:26

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