Stone bridge over the mill stream

I'm putting in a mill pond which served the now abandoned gristmill. There's a stream feeding the pond, and this stone bridge will take a road over that stream. I made a latex mold of the top part of a WS tunnel portal, and then cast a pair of these, much thinner than the original. I used a different casting for the roadside face, visible on the other side of the bridge. I used Rustoleum speckled brown spray paint, and highligted it with an India Ink wash.