How to apply designs to various slides (2002 and later)

PowerPoint 2002 introduced multiple masters and it is supported in the PowerPoint Object model too.
Let us see how we can assign different designs to various slides. The example below assumes that the presentation has multiple designs in it
 

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' Every slide has a Design object associated with it. 
' Set this property to the design you wish to apply to a given slide range.
' To assign the 2nd template to the 2nd slide.
' Note: If a design ceases to be used by any of the slides,
' it will be removed from the Designs collection unless the Preserved
' property for that design is set to TRUE.

With ActivePresentation
    .Slides(2).Design = .Designs(2)
End With

' To assign the 3rd template to a slide range
With ActivePresentation
    .Slides.Range(Array(1, 3)).Design = .Designs(3)
End With