Select a Flexible Duct and use the available Pet Palette commands to modify the duct shape. (Note that these commands will also allow you to create duct elements of extreme geometries that are not structurally valid.)
Move Node: Available from the Pet Palette of a flexible duct element’s internal node.
Insert Node: Available from the Pet Palette of a flexible duct element’s edge.
Stretch: Available from the Pet Palette at the end node of a flexible duct.