We all have these, especially those of us (geezers) that have been at it a long time. Here's a few of mine, please add to the list. ... Olive Oil .. after using everything by everyone for fretboards I like this best. Cheap , simple, organic, and it works. I use the extra virgin, not that it matters but I cook, so it's always around. Swallow a teaspoon yourself while your at it, it's good for you. ..... Tire levers.. get these from a cycling shop, hard plastic, cheap, indestructable. I have a set that lifts knobs off perfectly on one end, and the other end fits exactly in a Gibson tailpiece stud and leaves no marks.