How do I change the dielectric material for an existing polygon?
Geometry Elements - Dielectric Bricks, Polygons
To change the dielectric material, perform the following:
Select the polygon(s) for which you wish to change the brick material.
Select Modify => Brick Properties from the project editor main menu.

Select the brick material you wish to use for the selected polygons from the Brick drop list. Note that if you selected multiple polygons which use different brick materials, ''Mixed'' appears in the drop list as shown above. The brick material you select from the drop list will be applied to all of the selected polygons.
Click on the OK button to close the dialog box and apply the changes.