To make the mirror frame, Kevin first used his table saw to cut a 1/4 by 1/4 groove in the corner of the 1-inch square trim piece. This would create the little notches where the trim would rest on the edge of the mirror.
You could also stain or just seal the wood. But I’m not sure what I want to do with ours. I just love the look of raw walnut wood! A sealer would make it more rich and shiny.