How do I draw a parallelogram with a compass?

Draw a straight line. Choose two points on it at a convenient distance from each other. Using those points as centers, inscribe two arcs of the same radius. Draw a straight line on one side of the first line and tangent to both arcs. You now have two parallel lines which will form two sides of the parallelogram. Draw another straight line through both parallel lines. This will be the third side of the parallelogram. Use the compass to mark a point on each of the original lines equidistant from their intersections with the third line. Draw a fourth line through the latter two points. That line will be parallel to the third line you drew. You now have a parallelogram.