To add splash marks to the surface of a model water feature made with clear plastic sheet, you can remove areas of the surface texture to leave behind a circular ripple. In this pool you can see a ripple which was formed by applying a small amount of water to the almost dry surface of the textured pool. Where the water softened the acrylic, it was removed with a bit of paper towel and a cotton but, so that a depression with a surrounding line was left in the water surface. You can achieve the same result by building up your water surface layer with a brush leaving a circular area without the build up if you prefer. With a pin, you can add small water droplets to areas surrounding the pool, to imply a fish has just gone beneath the surface, or flashed its tail.