I'm just beginning to learn Blender, and I ran into a problem. I ended up with two separate meshes in one object. I want to attach their faces together, as if I had drawn and extruded one from the other. In this example, I have an octagonal prism that I want to attach to the face of a cube. How can I do this without remaking one of the meshes?

What I have now:

What I have now

I know that one way to work around it would be to simply move the meshes together so they overlap, but then they aren't actually properly attached, and won't move together/etc.

enter image description here

  • 1
    $\begingroup$ You will have to modify the geometry somewhat since the bottom piece doesn't have the same number of top vertices as the top piece. $\endgroup$
    – PGmath
    Feb 15, 2016 at 23:41

1 Answer 1


You can use either Boolean modificator (in Object mode) or Intersect tool (in Edit mode).

  1. Start with cylinder passing through cube.
  2. Cube and cylinder have different amount of vertices, hence cube should be edited in order to have roughly the same shape as cylinder has. It is possible to skip this and create intersection as is, however this way will create Ngons which may be undesired.
    One way to change cube accordingly is to bevel it. Select it and press Ctrl+B, 2 segments, low value of Offset.

    beveling cube image

  3. Add 1 loopcut per both sides of the cube. Use Connect Vertex Path (J) tool to connect corner vertices.

    editing geometry of cube image

  4. Select all, in 3D Viewport header choose Mesh > Faces > Intersect tool and in its options (Last Operator panel in the Toolshelf or F6) select Self-Intersect.

    using intersect tool image

  5. Select all again, press W, choose Remove Doubles. Note that you may need to enter higher threshold for Merge Distance, like 0.02.

  • $\begingroup$ I'm not seeing the Intersect tool. Is it in some addon? $\endgroup$
    – a52
    Feb 16, 2016 at 0:34
  • $\begingroup$ @a52 answer updated. This tool is present in Blender 2.72+ and it's located in Mesh > Faces > Intersect or you can press Space and type tool's name. See release video for more info on it. $\endgroup$
    – Mr Zak
    Feb 16, 2016 at 10:59
  • $\begingroup$ @a52 also note that you might end up with non-manifold mesh (because of internal faces). Depending on purposes of the meshes you can handle it in different ways; one of them is to press Ctrl+Alt+Shift+M and delete faces. $\endgroup$
    – Mr Zak
    Feb 16, 2016 at 11:49

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