: the idea would be to turn the 2 panels upside down so the back is exposed and
: butt them up against each other near (not necessarily on) the edge of the
: bench and clamp them in this position. . . then sand into this area
: w/ a grinder going the 12xthickness sanded thru ea way. sand sort of a
: dish or concave shaped depression stopping on the join as soon as the
: lowest(face veneer is reached).

: then lay in subseqently smaller layers of epoxy and glass, let set up and
: sand flushish.

As I read this, it sounds like you are digging out a shallow trench on the bad side of the plywood, and filling that with glass cloth and resin.

If that is right, then there are two problems. 1) You'll cut throuh the first layer of veneer and expose the middle core of the plywood. That usually is not the same color, so you'll have a 1 1/2 inch to 3 inch wide band of that color buried under your glass and resin. 2) You'll only be reinforcing the inside with your glass cloth. During the construction you'll be bending the plywood in such a way that the inside is compressed, and the outside is stretched. The glass anad epoxy on the inside is rather flexible and compressible. With no reinforcement on the outside you stand a chance of popping open the glue line. If you are going to just add to one side, you'ld be better off to splice in a piece of wood.Think of using a butt block, even a thin one recessed into the joint, and not glass and resin, as it will be stronger in that regard.

PGJ