Click Knit Surface
on the Surfaces toolbar.
Expand Surface
Bodies 
in the FeatureManager design tree.
Select all the surface bodies in the folder for
Surfaces and Faces to Knit 
.
Knit all the surfaces into a single entity.
Click Knit Surface
on the Surfaces toolbar.
Expand Surface
Bodies in the FeatureManager design tree.
Select all the surface bodies in the folder for
Surfaces and Faces to Knit .
Click OK
.
The Surface
Bodies folder now holds a single surface body.
Save the model.
