Demo 2. A partial reproduction of Sugihara’s (2016) “Right-Facing Arrow”. The original work is a cylinder with an open-top. Only the boundary contour of the open-top was reproduced by using computer graphics. The boundary contour is non-planar and it is 3D rotationally-symmetrical. A cube, whose center passes through the rotational-symmetry axis of the contour, was placed as a reference. The 3D rotationally-symmetrical contour and the cube can be rotated together about the symmetry axis by dragging the mouse over the image of the boundary.