I’ve used foam for landscape contours before and found the only drawback is that the foam is a bit flexible, so the pressure on its surface can cause indents. This is no big deal – unless of course, you’ve applied some plaster or spackle atop the foam, in which case it tends to flake off. With this, I chose to apply a coat of full-strength white glue and paper towels to the surface of the baseboard. This offered some distinct construction advantages: First, the baseboard is now rock hard ‘ much like a plaster impregnated cloth, the glue/foam has made the surface of the baseboard virtually bulletproof. Second, I’m more confident attaching my track to this rigid surface as it will be more secure than the foam and cardboard alone. Thirdly, it’s important to seal the foam. I will be using spray-paint to colour the track etc., and I really don’t want any chemical erosion on my hillsides.
It is also now apparent that the tunnel I planned doesn’t really have the necessary clearances to look convincing. One option would be to just have one track pass over the other via a bridge, but I didn’t do much detail work on the sidewalls of the tunnel and I don’t want to excavate more material.
Time to head to the sketchbook!