I haven't had that much fun since absorbing Walbridges book. ok,ok, here it goes: two layers 4oz s-glass oriented 45degrees on the inside with two layers of 4oz e-glass(high count?) oriented 45degrees on the outside. ??? My backyard testing gave me the sense that lot's o' e-glass does make things tougher and more brittle. Funny how a mind can get stuck on these permutations.