My brain must not be fully in gear today.....
the problem with the long list of ply that I found is that it was all
interior grade glue... not exterior as I stated above (guess the
mental clutch is slipping).

So now I think I will either do a layer of 1.5mm gl-2 finnish birch
followed by 6mm of chopped glass and resin, topped by another 1.5mm
birch ply (for 9mm of material) or 4 layers of the birch sandwiched
out with glass & epoxy to the desired 9mm.

Which of the above techniques will be stronger?

The birch is sold in 4'x4' sheets at around $24.00 a sheet plus
shipping (about $10.00). I am trying to also decide which will be more
cost effective as I haven't decided wich is more expensive, an extra
sheet of birch or the epoxy and glass needed to build a 6mm inner
core.

Any thoughts on which technique is more cost effective?

As for bending:

I will soak the birch in a very hot bath, throw in some amonia (into
the hot bath), and spot spray with water & heat it with a flat iron as
needed while applying it (a technique I saw described in one of the
model airplane building groups where the guy said he wrapped 6 inches
1.5mm around a pencil, in a very tight spiral).


Thanks,
Kevin