Funny you should mention that Handi. I just finished a shooting bench for a range that we are building at a friends house in the country.
I started with an old cafeteria bench and added 2" stainless angle and 2" stainless tubing until I had a strong frame. Then I topped it off with two pieces of 3/4" plywood, glued together with liquid nails and bolted to hold it, then Rhino lined the whole thing.
This thing is heavy and it is not portable. We also put an adjustable seat on it that slides up and down to accommodate shooters of different heights.
I would probably be interested in what you come up with for our new bench. Let me know when you've got it roughed out.