Making your own atlas stone costs a fraction of buying one pre-made, and the process is straightforward: you need a spherical mold, concrete, a release agent, and a few basic tools. Most people can pour a stone in under an hour and have it ready to train with in about a week. Here’s how to do it right on the first try.
Choose Your Mold Size
Atlas stone molds come in two halves that clamp together to form a sphere. You can find them from specialty suppliers like Slater’s or various strongman equipment sellers. Molds are typically made from fiberglass or ABS plastic, and both work well for home use. Fiberglass has a slight edge in durability over many pours, but ABS molds are widely available and perfectly adequate if you’re only making a few stones.
The mold diameter determines the stone’s weight. For standard men’s competition stones in the 220 to 265 lb range, you’re looking at roughly a 20-inch (51 cm) diameter. Smaller molds produce lighter stones. A 16-inch mold, for example, yields something closer to 170 to 180 lbs depending on your mix. If you want a specific weight from a given mold size, you can adjust with internal weights or hollow cores (more on that below).
Pick the Right Concrete Mix
This is where most first-timers go wrong. Your instinct might be to grab the highest-strength bag you can find, like a 5000 PSI high-early-strength mix. Resist that urge. High-strength concrete is designed for structural compression loads, not impact resistance, and it’s significantly harder to work with. The mix is stiffer, less forgiving, and more likely to leave you with a chunky, rough surface.
A standard concrete mix or a crack-resistant blend is a better choice. Some builders prefer a sandier mix or even stucco mix for better impact resistance and a smoother finish. The key issue is aggregate size. If the coarse gravel chunks in your mix are too large, they’ll create a rough, uneven surface that’s difficult to smooth out. A mix with finer aggregate fills the mold more completely and gives you a cleaner sphere. For the smoothest possible result, you can mix your own blend using sand and Portland cement, skipping the large aggregate entirely.
Prepare the Mold
Before pouring anything, coat the entire inside surface of both mold halves with a release agent. Cooking spray works in a pinch, but petroleum jelly gives a more reliable release and a slightly smoother finish. Apply it generously. If you skip this step or apply too thin a coat, the concrete will bond to the mold and you’ll spend hours chipping it free (or damage the mold entirely).
Set the bottom half of the mold on a stable, level surface. A bucket of sand works well as a cradle to keep it from rocking. Have your top half, clamps, and mixed concrete ready before you start pouring, because once the concrete is mixed you’re on a timer.
Mix and Pour
Follow the water ratio on your concrete bag precisely. Too much water weakens the stone and causes excess air bubbles. Too little makes it impossible to fill the mold completely. For a sandier mix, you may need slightly more water than a standard bag mix, but add it gradually.
Fill the bottom mold half first, tapping the outside firmly as you go. This tapping is critical. It vibrates air pockets to the surface and helps the concrete settle into every contour of the mold. Don’t rush this. Spend a solid minute or two tapping all around the mold with a rubber mallet or your hand after each addition of concrete. Unfilled air pockets become surface craters on your finished stone.
Once the bottom half is full, place the top half on and clamp or secure it together. Most molds have a pour hole at the top. Continue adding concrete through this opening, tapping periodically, until the mold is completely full. Overfill slightly, then scrape the excess flush with the opening.
Adjusting the Weight
If you want a lighter stone from a large mold, suspend an inflated ball or a foam ball in the center of the mold as you pour. This creates a hollow core and reduces the overall weight significantly.
Going heavier is trickier. You can add dense objects like steel weight plates, lengths of rebar, or scrap lead to the interior. The challenge is keeping them centered so the stone’s balance isn’t thrown off. One practical method: fill the mold partway, then lower the weight in through the pour hole once the concrete below is firm enough to support it without sinking. Window sash weights (the long, narrow iron counterweights from old windows) work well because their shape slides easily through the pour opening. Just be aware that tapping out air bubbles can cause heavy objects to shift, so work carefully.
Curing: Don’t Rush It
After pouring, leave the stone in the mold for at least 48 hours before attempting to remove it. Concrete reaches about 70% of its full strength after 7 days and doesn’t hit full strength until 28 days. You can carefully remove the mold after two days, but don’t drop or load the stone for at least a week.
During the first week, keep the stone moist. Drape a wet towel over it or mist it with water once or twice a day. Concrete cures through a chemical reaction with water, not by drying out. Letting it dry too fast, especially in hot weather, weakens the finished product and increases the chance of surface cracks.
Smoothing the Surface
When you pull the two halves apart, you’ll have a visible seam line around the equator of the stone. There will also likely be small air pockets and rough patches on the surface. Both are normal.
Start with an angle grinder fitted with a 60-grit flap disc to knock down the seam line and any large bumps. Then switch to a 120-grit flap disc for a smoother finish. For small holes and pits, mix a slurry of sand and Portland cement, press it into the voids, and rub it smooth with a wet hand or sponge. Let this patch cure for a day before grinding it flush.
Sealing and Applying Tacky
Raw concrete is porous and will absorb moisture, chalk, and tacky unevenly. If you plan to use tacky (pine resin grip aid), you’ll want to seal the stone first. A basic concrete sealer from any hardware store works. Apply it after the stone is fully cured and smoothed.
To apply tacky, warm it with a heat gun until it’s pliable, then spread a thin, even layer over the stone’s surface. Cerberus and Spider Tack are popular brands among strongman athletes. The sealed surface lets the tacky sit on top rather than soaking into the concrete, which means better grip and easier cleanup later.
Cleaning Off Old Tacky
After several training sessions, tacky builds up and collects dirt, making the stone slippery rather than grippy. The most effective cleaning method is an angle grinder with a flap disc, though it creates a lot of dust, so do it outdoors. For a less messy approach, xylene (available at most hardware stores) dissolves pine resin effectively. Apply it carefully in a ventilated area and follow safe handling steps, as it’s a strong solvent. A wire brush or a propane torch can handle light buildup between deeper cleanings.
What It Costs
A bag of concrete runs $5 to $10 and a single stone may take one to three bags depending on size. The mold is the real expense, typically $80 to $200 depending on size and material. A release agent, grinder disc, and sealer add another $20 to $30. All in, your first stone costs roughly $100 to $230, but every stone after that costs only the price of concrete. Compare that to $150 to $400 per stone from commercial suppliers, and the math works out quickly if you’re building a set of multiple weights.