Metal washcloth
It is mainly used for smoothing in the process of grinding or for applying wax during the finish process.
It is easy to make bars of various shapes for grinding bends and angles. Mineral materials such as segments of plastic tubes can serve as a suitable profile of a bar for working with concaves. You can work as a file, holding both ends with your fingers to give stability to actions directed across the fibers. The grinder method is very universal. Here one hand grinds, the other turns the part.