I am doing a cake for my sister's 10 year class reunion at the end of this month, and our High School has an Arch over the front entry way that has become somewhat symbolic of our school. She requested that I do an arch cake- my first thought was a sculpted cake shaped as an arch, I then realized what my capabilities are and how much I would have to charge, and I don't think they could afford it, and I am not sure I am capable of doing one. So, my thought is to do tiered cake with an arch on top- I use BC and MMF, and have not experimented with gumpaste or anything else........what would you guys use? Here is a pic of the arch:

that can be done with either royal icing or fondant. if you do it in royal icing make sure you do more than one for breakage.

Which ever you use do make at least 2 of them. Put toothpicks or sucker sticks in the ends to help hold it up on the cake.
If you use fondant I suggest you add some Tylose or Wilton's GumTex to it. (About 1/2 teaspoon to a golf ball size piece.)