ArtWidth Property
Returns or sets the width (in points) of the specified graphical page border. Read/write Long.
Example
This example adds a 6-point dotted border around each page in the first section in the selection.
Dim borderLoop As Border
For Each borderLoop In Selection.Sections(1).Borders
With borderLoop
.ArtStyle = wdArtBasicBlackDots
.ArtWidth = 6
End With
Next borderLoop