Thanks all... for heavier hardware I do recommend 6mm vs 3mm.... it's only adding an extra 6mm width to the perimeter... and shelves 3mm per layer... not much real estate surrender.

It does vaguely steal from the torsion box concept... the larger frame over exploited the idea considering the weight vs span vs small glue up surface.   

If your first cut is too short... Take the second cut from the longer end... LBD