In the attached file, I want to mirror "Side rt" to form "Side lt" and don't want them to be merged with "Drwr front".  But SW wont allow mirroring the Side rt (plus the extruded cuts on Side rt) unless the Side rt is merged.  The error message when attempting unmerged suggests I should select bodies to mirror.  My search of Help didn't return any info on how to create bodies, and a video in thread earlier this year showed mirroring by the selection of an extrusion as the "Bodies to mirror".  Simple.  Why not in my file?

Bevin.