Rendered views of the probable structures containing the observed echoes. Top row: The CD nebula. Second row: The NH nebula. Third row: The CS nebula. Fourth row: The CS hourglass. For these top four rows: left column, the face‐on view of the complete structure; second column, the western half, viewed from the east, showing a clear view of the interior; right columns, face‐on and side views of the complete structures in monotone gray, overlaid with actual echo points from Fig. 15. For the bottom row: (q) The western halves of the CD and NH, and (r) NH and CS nebulae, viewed from the east. (s) The northern halves of the CD and NH, and (t) the NH and CS nebulae, viewed along the inclination axes from the south. See text for colors.