Sorry to disappoint you, but wood working is one my my favorite hobbies. Possibly more than music. I do quite a bit of turning, and have just started carving. So far I have made many pens, letter openers, bowls, and vases. However I have never tried to use cork. Cork is a type of bark. Bark is carvable, but very difficult due to the crazy grain. If I had access to cork trees I would have already tried! As for using sandpaper, you would be sitting there forever sanding. If you rough out the cork with a small knife, then sand it will be much faster. Next fine tune it to fit perfectly in the hole. Sound like a lot of work? Probably, but if you want something and can't find it, it might be best to do it on your own-or at least try. It might actually work. If you want pictures to prove all this, just ask. But I have no idea on how to post them.