I made one about thirty years ago also. My son was seven, so the gun was built on a much reduced scale. It actually was a trade gun instead of a fowler. It was .410 gauge and the barrel was about 20 inches long. since it was a trade gun I was able to make all of the hardware. The barrel was a heavy round shotgun barrel I found. I hand filed octagon flats, and wedding bands into it. I got the pattern from a paperback tradegun book that had some full sized patterns also. I still have that gun somewhere out in the shop.
Hungry Horse