I am building a 6 foot long shelf that is going to be supported at the ends (no option of support in the middle). The shelf needs to support about 50-
70 pounds of weight (stereo equipment), so the "sag" (or deflection) in the center is going to be a problem. I plan on building the shelf as a hollow box, and using steel angle iron on the inside as a stiffener.Just out of curiosity -- what commonly available wood product is best for resisting deflection under a continuous load (i.e. shelving)? The easily available ones at my local lumber store are: laminated pine, mdf, playwood and particle board, I am assuming that the laminated pine would be best, since all the grain is running longitudinally. Is my assumption correct?