This inexpensive little mold sure saves time structuring rock walls that show through the tunnel portals. My new layout has ten tunnel portals into my perforated mountain, so the savings is significant. It takes a couple days to dry a tunnel half, so one has to start accumulating molded pieces. Then the work of tunnel building goes smoothly. It took about 3/4 cup of SculptaMold per piece, and I imbedded a strip of medical gauze for extra reinforcement. My layout is N scale but I made all the pieces full size and cut them to fit an I create. The cut-off pieces get used too. No waste. The Woodland Scenics Earthtone paints can do a realistic job, but the walls are hard to see in detail, so I made them stone gray, not in 50 shades. I made my panels removable by gluing bamboo skewers to the corners and sticking the points into the 1 inch Styrofoam that covers my layout. I needed to get access to the IR detectors and signal circuits at each portal. The tunnel pieces and portal lift off easily with no hinged moving parts.