Is there a was to set up duct items (other than straight duct which already has a auto length of 60" because of sheet metal size) with a auto length? For instance I want  to set up flex connectors (or canvas connection) for 8" length. It is 3x3x3 flex, minus a inch for flex allowance. 9-1=8. So when I make a connector, if it has S+D (-1/2") and has a 1" flange out (-1"), it will be 6 1/2" long. I want the flex connector length to adjust for connector type. Thanks