A tool for the internal high-pressure shaping of a workpiece, in particular for producing a tubular structural component for a motor vehicle, is provided. The tool includes at least three movable tool segments, which bound a shaping cavity for accommodating and shaping the workpiece. The movable tool segments, at least in some sections, completely form the shaping cavity in a closed state of the tool. A method for shaping a workpiece by internal high-pressure shaping is also provided.