Comparison of the 3D models of Hb 12 with various orientations and colour-composite HST images of PNs M 2-9 and Hen 2-320. Upper row: 3D mesh models of Hb 12 viewed at angles of 45°, 19°, and 0°, respectively (0° being the sky plane). The innermost lobes of the models are shown in orange to better show various structures. Middle row: corresponding rendered images of 3D mesh models. The 2D ring elements in the outermost lobes are not shown in the meshes. All renderings in this figure are applied using a Gaussian blur. Lower row, from left to right: grey-colour HST F160W image with acomposite-colour CFHT insert (made with Kc (blue), H₂ (green), and Brγ (red) bands) of Hb 12 and composite-colour HST narrow-band images of M 2-9 and Hen 2-320 (Hsia et al. 2014). The HST image of M 2-9 is created with [O III] (blue), [S II] (green), and [N II] (red) filters. The locations of the bipolar lobes and the 2D ring structures are also marked.