I didn't leave any metal in either of my boats. In the first one, I did use staples to hold the strips to the forms, since I painted the boat and the holes left by the staples were hidden. The gunwales were attached with screws until the epoxy set; I then removed them and plugged the holes with dowels. For boat two I used clamps (lots and lots of clamps [fortunately in the five or so years between boat projects I had accumulated quite a few of them]) on everything, even though I also painted this boat.

I would have preferred to finish boat two bright, but... My building space was 11 by 12 feet, and the boat was a sixteen-footer. Serious problem, solved by constructing the boat in three pieces, and joining them with pseudo-scarf joints. This made for distinctly ugly spots, which I had to hide with paint.