An f-hole cutter is used to cut the circular holes at the top and bottom of the f-holes. This is the first step in cutting out the f-hole. Commonly an f-hole cutter is used to prevent grain tear-out. A pilot hole is drilled and the f-hole cutter is used to make the final cut, a bit from both sides.
My issue was that my f-hole cutter came in a bag. After honing the cutters, I had nowhere to put them neatly, so they wouldn’t get damaged. I solved this by building a small box. The box is maple with paduke top and bottom, finished with tung nut oil.