Working with Markups > Measurements > 3D Measurements > To Create a Mass Properties Measurement
  
To Create a Mass Properties Measurement
1. Click Markup > Mass Properties. The Measure Mass Properties dialog box opens.
2. Select an entity to measure. The entity’s property measurements appear in the graphics area and in the Results panel of the dialog box.
3. Press CTRL+Select a second reference entity. The sum of the references’ measurements appears in the graphics area. The measurements of each reference and the sum of the measurements appear in the Results panel of the dialog box.
4. Click . The measurement is saved to the annotation set.