Here is a 14″ Atlas Stone Mold ready for Spartan and strongman competitions. It lets you make your own Atlas stone in your backyard. Depending on your concrete, your stone will weigh from 110 to 115lbs. You get two halves to make one complete round stone.
You can secure the two halves with zip ties or 14 x 3/4 sheet metal screws. More info is available here.