The first file I have modified is a barrette needle file. It has 3 very sharp edges on the back and 2 sides that need to be rounded to make it easier to use. Rounding off the back edge also makes the file much thinner and more useful as it can be used in smaller spaces. Many files like this barrette file have a really sharp pointed tip and I also round this point so it can't cause any damage. You can see from the photos of the tube earrings that I'm making that the original barrette file could have easily gouged the other tube settings, but once the file is smooth and thin it is easy to maneuver around each tube without contacting the other tubes. The same goes for wire designs, having a thin rounded file means it will be much more useful in getting into cramped areas.