Mike -- If you have a version of Geomagic that allows Configurations, you merely create a Configuration in which the part in question is scaled to create the mirror you desire. If you do not have a version that allows Configurations, then you create a second part where the geometry from the original part is Boolean Added to your workspace and then scaled to create the appropriate mirror. You will need to name the second part appropriately as any edit to the original part will be passed along to your mirrored part.