Tell us the recipe you used, the dimensions of the stepping stones, how long they were unmolded before they broke. Did you unmold too soon? Were they too thin? Did you mix the cement mixture correctly. Hypertufa isn't the best thing for stepping stones.

Billie is right about hypertufa and stepping stones. But, if you're making wall pavers, you aren't walking on them or putting undue weight on them. I've made small paver stones by using the plastic type segmented serving dishes. There's usually four compartments. I just line each segmented compartment with plastic and pack with mud. I pop out a day later and use them as small paving bricks.