Don't model the diamond pattern. That would be a waste of time and only serve to make your model heavier and more difficult to work with. Call out the material on your drawing and/or use a hatch pattern on the drawing views for a pictorial reference.
What Cowski said.
Occasionally we have to model cross hatching in order to machine it into our molds. It's a pretty awful experience. NX slows to an absolute crawl.