My recomendation is to build a heavy bench from 2x4's. Use 2x8's for the top. That will easily support a vise and heavy use with hammers, etc. For modeling, just lay a hollow door on top. It will be plenty flat.

All that sandwiching is a waste of time and material. I use an old glass door when I want an extremely flat/smooth surface.

Tom

Man WAS meant to fly. That's why we have credit cards.