Constrain your hypertufa in a mold or form for the best results. But what do you use for a form?
Look around you; I'll bet there are some molds or forms right in front of you. They can be free or cheap, plastic bowls from the thrift store or a garage sale.
I've made great garden planters from all kinds of found objects, from baskets to styrofoam.
Sometimes it's best to use a form release such as vaseline, Pam or a liner of thin poly (or not so thin; check out the page on textures).
Here are a few forms to try for your hypertufa projects;
You'll look at things with new eyes whenever you're shopping or browsing a garage sale; anything with some flex, like a plastic container that is bigger at the top opening than the bottom will work.
Baskets woven from wicker or twigs can have one last hurrah by being used for a form.
Buckets, round or square, plastic ice cream containers, even planters make great molds.
You don't have to fill them up completely; I've made some really nice shallow planters for succulents by only making the hypertufa pot a few inches tall in a large square bucket.