The CADspan plugin created by LGM is a tool that prepares your 3D model for 3D printing or prototyping. To be honest I have not actually used this plugin as I do not have a 3D printer nor do I use them. But I think this plugin is important to mention regardless.
This plugin allows you to to unify the entire model into one “shrink wraped” surface and create a final .stl file. It also fixes any problematic areas automatically such as fixing co-planar and coincident faces. And it highlights areas that may give you issues so you can fix them without major modifications. But a drawback is that you might need to prep your file before using this plugin so that it works correctly but this process is still much faster than having to setup the entire file yourself.
Overall, the CADspan plugin created for Google SketchUp is a great solution for creating a 3D print file straight from SketchUp. As I mentioned, I have not actually used the plugin so I do not have a grade for it, but this is worth the mentioning. At the time of this review this plugin is free and is available at CADspan.com.