RigidPolygon Command

RigidPolygon( <Polygon> ): Creates a copy of any polygon that can only be translated by dragging its first vertex and rotated by dragging its second vertex.
RigidPolygon( <Polygon>, <Offset x>, <Offset y> ): Creates a copy of any polygon with the given offset that can only be translated by dragging its first vertex and rotated by dragging its second vertex.
RigidPolygon( <Free Point>, …, <Free Point> ): Creates polygon whose shape cannot be changed. This polygon can be translated by dragging its first vertex and rotated by dragging its second vertex.

The copy will join in every change of the original polygon. If you want to change the shape of the copy, you have to change the original.