I cut out the profile boards and placed them up against the backdrop. A small ruler is holding the boards up. I "lived" with this for a day or two to see if I liked this profile, and if I could visualize a nice rolling hill with lots of trees on it. Note that these boards will not be visible once the scenery base has been installed, so it doesn't matter what is on them.
When I made the decision that I was happy with the profile, I used a collection of left-over scraps of wood to form some supports to hold the profile board in place. These were glued together with wood glue first. Next, I glued them in place, gluing both the benchwork contact surface and the profile board surface. This means the board is in there good and solid, however, should I want a different scenery profile, I can use a hammer to quickly break them loose and remove the profile board.
The next photo shows the step-by-step construction method. Individual strips of cardboard were first bent and glued to the profile board in the back. I then shaped and trimmed the strip so that it just fits under the sub-roadbed, and glued it in place. After I did a section, I went back and weaved horizontal strips in between the previous strips. This forms a solid webbing that is quite strong. It is easy to cut a strip to make it shorter or to glue another strip in to make it longer. The idea is that there is a down-slope from the track (for drainage), and then an up-slope toward the back of the layout for the hills. I used hot glue to glue the cardboard strips in place. It takes only a few seconds for each glue spot to dry and it goes remarkably fast.
Here's the finished section. I left a gap in the middle because that's where the two modules meet.
I decided to start painting the backdrop with some light-colored hills. This helps set the "mood" for this area as I start to work on the 3D sections of the hills. I used Greg Gray's video as my guide for how to paint backdrops. I have watched the video many times, and I always go through the whole thing again when I get ready to paint a layout's backdrop.
I used Woodland Scenics' plaster cloth to put a layer of the material over the cardboard webbing to form the basis of the scenery layer.
I only put down a single layer of Woodland Scenics plaster cloth, because that stuff is expensive, and because I always follow that up with some layer of Sculptamold anyway. I followed the steps in my article on scenery base. I used the "ground goop" to form the final layer of the scenery base.
The ground goop takes quite a while to dry, so it easy to add some rocks and the basic ground cover to make the area not look so barren for the time-being.
Here is a view of the right half of the center section.
With the basic scenery base finished, I could return to the backdrop painting. In addition to painting some distant hills, I also started painting some trees that are more closer to the viewer.
I did a similar thing on the right half of the center section.
This is a nice overall shot of the center section of the layout as it stands now.