Time for another round of updates! Today I focused on building the terrain that would be above grade, i.e. the hillside next to the tracks. To do this, I decided the quickest way was with expanding foam. The stuff is flexible, carvable, and can be stiffened with layers of paint and fill material. This hill does not support much weight, and so it doesn't have to be structural in any way. Being flexible means this hill can be bumped around (such as when traveling) and still maintain it's shape. By contrast, insulation board has a tendency to dent when struck by something. The insulation boards redeeming quality, however, is it's stiff and can hold weight. The modules are 18 inches wide, and the main line will be recessed 6" from the downhill (North) side of the module, leaving 12 inches for the yard tracks and for the hillside. The hill, once carved down, will take up about 5 inches of space on the module. This leaves about 7 inches of s...