I can't tell you how much I wanted this tool to work! I was so looking forward to using it. First, the package says nothing about putting the metal below the guard, so thank goodness for the guidance on your website. Try as I might, and I do have decent hand strength, I struggled to get the punch to go through a 24g copper sheet. On the third try (I gave up on the first two) I managed to punch a hole. It looked like a misshapen teardrop, and the burr on the back was enormous. Perhaps I can use this as a dimple punch, but that's about it. Very disappointing!