The doorstop.
 
When building a doorstop the carpenter will want to begin with a square piece of wood. Draw a line from one corner to the other and cut with a coping saw or a hand saw (figure 1). The two halves can then be sanded with a medium grit paper to remove any splinters that may cause harm (figure 2). Place the bloock of wood on the floor in a position that will intercept the art of the door's travel (figure 3. Apply even force to the back of the door and the doortstop forcing the lip of the block under the edge of the door, thereby obstructing movement (figure 4).