create solid full for 3d printing in stl

[cassandrarchitecture]

Hello, I need to print an object in 3d, but obviously it is necessary that the object is a full volume. I read that rhino does not work with solids, but with nurbs and surfaces, in my case the object in question is an open polysurface without thickness. I tried with Boolean subtraction and subdivided, but it's like rhino couldn't really see this polysurface. someone who has already had my own problem and who can help me?
I'll attach the photos.
Thank you.

 

[Utente cancellato 70856]

I did not understand why you tried with Boolean subtraction and divided
Have you tried extrusion or offset?

 

[cassandrarchitecture]

Yes, but the surface does not increase in volume. comes out a strange shape without thickness

 

[TECNOMODEL]

depends on what you need for the press.
an option could be extruding the external and internal profile, cutting it with a floor, building a flat surface and joining the whole.
from what I see that surface is "bruttina", I have idea that there is a little work on it to get something good.