The mountain range is in, as well as the opposing side ridge. Plaster cloth, wadded newspaper and pieces of rigid foam were used for the basic support. I’ll shoot some spray foam along the inside for more structure and support for trees later on. The back and sides will remain open, but will be framed with some wood and have access panels (see through?) in case of a derailment inside the mountain. The tunnel openings are rough until I decide on portal(s) and final positions. A bridge will span the main mountain and the ridge, with a track passing below to behind the range.