Mix the soil. It will often have a high concentration of clay to provide enough stability for the pitcher. According to Baseball-almanac.com, a good soil composition will consist of 40 percent sand, 40 percent clay and 20 percent silt.
Measure the diameter of the mound and the distance from home plate. According to Sportsknowhow.com, a regulation Little League mound is 18 feet in diameter, and the center of the mound is 46 feet from the back of home plate. The mound generally is 10.5 inches higher than the level of home plate.
Build the mound up an inch at a time. As you add each layer, tamp or roll the soil, keeping in mind that the mound will slope towards the batter's box.
Keep the soil rolled evenly to prevent injuries to pitchers. From the center of the mound, the slope should decrease one inch per one foot in all directions.
Add the pitcher's rubber. This is the plate at the top of the mound, where the pitcher begins the throwing motion. According to Hksportsfields.com, a standard pitcher's rubber is 24 inches by 6 inches. Use a carpenter's level to make sure the rubber stays flat while being installed.