A coarse and abrasive tool made of metal (usually steel). The abrasive surface has many pointed teeth shaped like tiny pyramids, and typically the surrounding surface is perforated so that dust doesn't clog it. Rasps are used in shaping and smoothing wood, plaster, ivory, stone, etc. Files are generally more finely abrasive than rasps, while rifflers are the most finely abrasive of all rasps.Also see surform.