Onto the roof...
Since I'll be creating a completely new roof section I'll need to meet the stock curve. To accomplish this I start with some scrap 3/4 inch plywood. I then measure the front section of the roof's curvature. From the measurements I create and ark on the plywood. Then I rough cut with a bandsaw and clean up with a belt sander.
Now I create a wooden frame to hold the arc molds in place and at the right hight.
Verifying the two pieces are the correct hight I place a strait metal bar across the gap.
Next I cut a piece of 20 gauge steel to fit into the gap. I cut 2 inches longer than I need to rough fit everything and slide it under the current roof sections
The roof is marked then cut to fit. As you can see from the additional line I messed up, luckily I caught it before I started to cut. Measure twice, cut once!!!