# Attaching one face to another

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:

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.

• 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. – PGmath Feb 15 '16 at 23:41

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

• @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. – Mr Zak Feb 16 '16 at 10:59
• @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. – Mr Zak Feb 16 '16 at 11:49