Position your sand trap so that it has plenty of rough grass surrounding the new addition to your backyard green. This area will not need to be manicured much, as letting the grass grow high will help simulate actual course conditions and improve your short game.
Dig the hole for your sand trap and make it no longer or wider than 5 feet by 5 feet. Most golfers prefer to have no more than two sand traps on their backyard green.
Form the walls of your sand trap by removing the grass from around the perimeter of your sand trap until you're satisfied with the size and shape. Dig from the outside to the inside of the sand trap.
Form the slope of your sand trap once all of the grass is removed. Generally, most golfers prefer a slope of two feet and later decide whether to increase or decrease the slope size.
Install a side wall with a horizontal floor base that will create a drainage system for water to be removed from the sand trap. The drainage system should be the entire length of the trap and approximately 10 to 12 inches deep inside the trap.
Fill the sand trap with sand. The sand will flow to the center due to the slope of the trap. Continue to add sand until you have achieved a depth of six inches, and then evenly distribute the sand until it conforms to the slope of the trap. Remember, using sand that is too fine can lead to the need to replace it inside the trap continually due to displacement from high winds.