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iOh, I see! I hadn't considered that the OP might be trying to create a symetrical picture from one half...

In that case, and considering we're in the OOP forum, I suggest that it be done with...

Make yourself a small image - say 4 rows each with 6 elements. Make it out of 24 small squares of paper (mark or colour them so they can be easily identified).

Now reflect the image: that is,...