You can convert placeholder duct to duct with fittings. The type properties of the placeholder elements determine the fittings to add. For example, if a duct placeholder is created with a type of rectangular duct with taps, then the placeholder elements will be converted to rectangular duct with taps instead of with tees.
- Select a placeholder element, segment, or the entire placeholder layout to convert.
- Click Modify | Multi-Select tab
Edit panel
Convert Placeholder.
The placeholder duct is converted to duct with fittings.
Note: If 
Show Related Warnings is available on the ribbon, you can click it to review warning messages related to converting placeholder duct layouts.
Show Related Warnings is available on the ribbon, you can click it to review warning messages related to converting placeholder duct layouts.