this looks very interesting, but I am not sure if this is a device to puncture letters. I have never seen such a pattern. The "spikes" are very close together and they seem not very deep so in case of a "thick" letter they may not go through the paper.
Also the area seems quiet small. But all of this is hard to judge just by seeing the pictures.
What is the size of this device? How does the pattern look like after treating a letter? Can you please try it on a 4 layer paper and show an example how it looks like afterwards?