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For example, I have a human head model, which is cut in half, because i want to mirror it. But the problem here is that some faces are over the Y axis and some do not touch the axis. When I then try to mirror this shows up, where let's say some points don't touch and other ones, where faces are over the axis just collide. Is there a possibility to align the "edge" faces to a certain axis, so the mirroring becomes perfect?