One, two, three ... three times at the other ... so eight specific actions by him, knocking it with another stone, to take off a flake, and to leave this almost straight line, which is a sharp edge.

To make clean straight folds in cardboard, first make a crease along the line with a blunt edge such as a spoon handle, then fold against a firm straight edge.

From the side, the front line is perpendicular and straight, coinciding with the maxillary edge or slightly projected forward.