If anyone is interested in making an Atlas Stone this is a GREAT site:

http://www.bodyresults.com/S2stone.asp

Lessons Learned:
I followed the directions, used a kids bouncing ball from Target and instead of cement used concrete. Little did I know there was a difference. The hardest part is the plaster mold. USE A LOT OF COATS!! After a failed trial with a smaller ball I realized I needed to use 2 or 3 coats of plaster. It ended up being about 1.5 to 2 inches thick. I also ran out of concrete and had to make an emergency run to Home Depot, so make sure to buy 2 or 3, 80 lbs. bags depending on the size of the ball. I believe mine was 46" in diameter.

Once the concrete was dry I used cement filler to fill in the gaps and make a smoothed out ball. Then used cement sealer when the filler had set. The ball ended up running me $70 and weighed in at 135 lbs. I'd like to make a larger one but this size works great for overhead military presses as well as pushing it for distance. When using it in this manner it works great for a wrist, forearm and shoulder developer.