After knowing the Feynman puzzle, I think this is probably more correctly described as a reversing mirror. If you look into a metal spoon, you'll see both X an

After knowing the Feynman puzzle, I think this is probably more correctly described as a reversing mirror. If you look into a metal spoon, you'll see both X and Y reversed. So I'm wondering if you could make this mirror simply by only curving the horizontal part. That's kind of what it looks like in the photo. And if so, why didn't someone think of this early? It's quite obvious.