SketchUp Solid Inspector²
For 3D printers it is necessary that the 3D models to be printed consist of closed volumes.
With the SketchUp extension Solid Inspector² it is possible to check your 3D model for gaps and errors. How to install extensions generally, see here.
At the beginning the model is examined and the errors are displayed in a list. Some errors, such as a reversed direction of the faces, can be solved automatically. Other defects, such as incomplete surfaces, must be repaired manually.
If "No Errors" is displayed, the model is ready for the 3D printer.