Select Start>NC Manufacturing> STL Rapid Prototyping. The STL Rapid Prototyping workbench is displayed and ready to use.
Open the GettingStartedSTL.CATPart from the samples directory. It is a hairdryer, made of surfaces, with a gap and a hole in it.
Click Tessellation and select the hairdryer. Click Apply and OK. You can see clearly the hole and the gap in the tessellation.