Just ten minutes ago I laminated three layers of 5 ply quarter inch stock to itself for a bulkhead/frame member, one of hundreds in my lifetime. The issue to remember is that you will not need to worry too much about strength because almost any glue with moderate pressure will do well because the stress loads usually never exceed the strength of the bond due to such a large surface area bonded. That said, the best glue is low viscosity polyurethane like Gorilla glue, because it will expand into any voids from unclamped or lightly clamped areas like sandbag weight. It pays to roll it on for uniform coverage. I think epoxy is overkill in this type of bond. PL Premium polyurethane construction adhesive (identical to 3M 5200 at a fraction of the cost) also works well for thicker plywood.
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