def METHOD_NAME(self) -> list:
    """
    Compact (lower-level) JSON formatting of a Polygon3DBox.
    This format follows an API understood by mathics_threejs_backend.
    """
    # TODO: account for line widths and style
    if self.vertex_colors is None:
        face_color = self.face_color.to_js()
    else:
        face_color = None
    if face_color and len(face_color) < 4 and self.face_opacity:
        face_color = face_color + [self.face_opacity.opacity]
    data = convert_coord_collection(
        self.lines,
        "polygon",
        face_color,
    )
    # print("### json Polygon3DBox", data)
    return data