This example adds an oval to myDocument
and then specifies that the oval be extruded to a depth of 50 points and that the extrusion be purple.
Set myDocument = ActiveDocument
Set myShape = myDocument.Shapes.AddShape(msoShapeOval, _
90, 90, 90, 40)
With myShape.ThreeD
.Visible = True
.Depth = 50
' RGB value for purple
.ExtrusionColor.RGB = RGB(255, 100, 255)
End With