After receiving a new small one-piece keychain tool in the mail yesterday (a gen 3 skull tool from PockeTTools), I realized I needed a nailfile. It occurred to me that it would make keychain tools so much more useful if they incorporated a short file somewhere on one edge. To the best of my recollection, none of my little keychain tools (like the Skull tool for example) have this feature. The gen 3 Skull tool has a half-inch long flat edge right above the skull's eye that would be a perfect spot for this. Mine already has some striations in this area that have been roughly smoothed, and if they hadn't been smoothed, it looks like it would work almost perfectly as a fine file edge. I hope some of the tool producers will implement this additional feature in their future designs.