AW2EOD,
I know there was a site that sells carved tufa in various shapes, and they had a large arch. You could certainly use something like that... I can't find it right now, but here is a link to a canadian site that sells tufa in bulk Then you could just carve out the shape you want. (Tufa is quite soft and easy to carve, usually.)
I know there was a site that sells carved tufa in various shapes, and they had a large arch. You could certainly use something like that... I can't find it right now, but here is a link to a canadian site that sells tufa in bulk Then you could just carve out the shape you want. (Tufa is quite soft and easy to carve, usually.)
