If you want a real wood one I have about a hundred real wood arches here.... it would however probably be expensive to ship one. They vary in length, radius, width, and thickness. I have them in poplar and mahogany. When we bought this property a couple of years ago it used to be a millwork and they were left here. Some of the larger ones would easily cost over a grand to have made. I have been selling them locally for $50 to $150 each. They are custom made glue-lam from many thinner pieces. For use outdoors they would need to be well sealed. I stood 3 on end here and made a barrel front wall with them and clear acrylic to make a special room for our Mimaki printer to contain the fumes and eliminate dust in there.
Here are a few of them as well as the print room.