As mentioned above, you can make a .3ds extruded object by doing a "live trace" from an arch photo .jpg, and used the resulting .3ds object in TFP.
See attached TFP render of wrought iron .3ds black arch decor on wall.
Also note the painted arch on the wall in a contrasting color (instead of building a real arch wall) as a faux effect. Made a .jpg image using photoshop (any similar prog will work), and applied that to the wall as a material. (see example .jpg)
Again, sharing these ideas for your potential use.