Select a location relative to your putting green that gives you the best practice. You will want it placed in your yard so that it is fairly level and approximately 10 to 15 feet away from your putting green. This will help to keep sand from always spraying onto your green. To determine the size of sand trap, take an extension cord or water hose and experiment with different shapes and sizes. Take your time and chip a few shots from the area to the green to make sure it works for you. When you are satisfied with the shape and size, mark the outside perimeter of the shape with a can of spray paint. This marked area will be used as a reference point while removing the existing grass.