The fusion fiber is very easy to use. Comes in white and you mix acrylic paint and water with it to make it the color you want. A nice feature of the fiber is that you can re-wet it and re-shape, re-use it after it's dried, handy if you decide to change your layout or if you decide you don't like the way it looks. Paint can also be applied to it after you apply it to your scenery. Just brush or trowl it into the fiber, you can also do paint washes with it (just let watery wet paint run down it and it looks like the weathered effect on rocks). Scenery items can be placed in wet fiber and then when it dries they're sealed in like they were resting in concrete. If you want to remove them later, just re-wet the fiber and pull them out, fiber cleans off the item with a little water.
$20/bag and that covers 20 sq ft, or you can get the close out bulk fiber that will cover 30-40 sq ft a bag at 6 bags for $100. The model railroad guys use this stuff a lot.
All in all this is a good product that when combined with other scenery products like Woodland Sceenics can add some nice details to your layout.
Various colors of acrylic paint were mixed with fusion fiber in small batches and then applied in layers in this area. Moss, turf and some plastic plants add to scenery. Blue acrylic paint and fusion fiber used to make river.
Several different paints brushed into wet fiber to give colored rock look. Natural stones added near river.
Styrofoam blocks covered with fusion fiber and moss form rock formations / track supports.
Black paint mixed with fusion fiber to simulate asphalt under the officials office and pace car area.
The tunnel turn with various shades of fusion fiber applied over cardboard and drywall tape.
Backside of tunnel turn and outside of final turn.