Look at Dwight's "cutting planez.jpg", change the Fill Material & Edge Pen of Cuts from Custom to Use Element Attributes, and the materials will be as assigned to each element.
David
David Maudlin / Architect www.davidmaudlin.com Digital Architecture AC27 USA • iMac 27" 4.0GHz Quad-core i7 OSX11 | 24 gb ram • MacBook Pro M3 Pro | 36 gb ram OSX14