The Mirror Tool plugin created by an unknown author at the Ruby Library Depot is a useful tool to have when using SketchUp. It allows you to mirror as you would in AutoCAD.
To use the tool all you need to do is click the object you want to mirror and click the “mirror selection” button. Then you can signify the mirror line simply and click enter. This tool though also allows you to keep selecting axis’ to accurately mirror the object the way you like. This comes in handy particularly when you need to mirror about an axis that is not one of the main axis’ on SketchUp.
Overall, the Mirror Tool plugin at the Ruby Library Depot is an essential plugin to have especially for AutoCAD users. At the time of this review this plugin is free and is available at the Ruby Library Depot. I give this plugin 5 out 5 stars!