I had wondered about Jerry or Gerry!
Two details I failed to mention regarding how to cut the arches - (1) I cut out a template out of 1/8" plywood to serve as a guide for the hot wire. The template, which I did not throw it away but can't find it or the pictures, is shaped as the inside of the arches, so I just secured it to the pink foam with a couple of coarse drywall screws, and went around it with the hot wire. The only challenge is to keep the wire perpendicular to the foam. (2) The Hot-Wire is from Woodland Scenics.
Alex