That should work fine with the molds. You can mix your own concrete with as much cement and aggragate as you like. You can get a smooth finish by using a scree (I think that's what its called) where you pour your concrete and smooth the top as you go. The plus to using a mold to make the stones is that the mold has a smooth bottom as you pour the concrete in, and when you unmold, you turn the stone over so the smooth bottom becomes the top. Cement and sand mixture is plenty strong if it is thick enough, at least 1.5 inches.

I read instructions a couple days ago about turning them over after they cure, but I was hoping to leave them in place so that each one will fit perfectly in the mold where they are. I would put plastic (or maybe landscape cloth)in the mold, then tear off to the edges of the cured stone.

I'm also wondering about color. Mixing it in would be easier than painting them afterward, but I really don't want them to be totally the same shade throughout. Maybe swirling a little cement dye into the mix? What do you think? I'm wondering if it would be almost as cheap to buy readymade stones. Sure would be less work. We're in our 70's and have nearly worked ourselves to death landscaping since moving into our new home 1 1/2 years ago. We're almost done. Last summer I made 50-some stepping stones for a patio and we laid broken concrete for another one. Planted a ton (seems like) of shrubs and plants, made a big dry river bed, spread gravel and lava rock and as soon as we get a fence built we'll cover the rest of the yard with various paths, bark, shrubs and garden art. Then maybe we can sit back and enjoy.

laura, Sounds like you've done some wonderful work in your garden in the short time you've been there. Are you making the garden art?
You can dig molds out of the ground and just pour in place. No you don't turn them over. Depending on the USDA gardening zone you're in would best determine which mix you use, what thickness and reinforcement you use. Why would you line the ground mold with plastic or garden cloth? Concrete (portland cement, sand and gravel) will give you a smooth finish, the gravel doesn't sit on the surface unless you don't mix right or you intentionally expose the gravel. You can also use a magnesium trowel, it settles the gravel and brings the sand to the surface but it's not necessary. You can add dye but the drawbacks are the colors can be off. I've made planters that turned out a nasty yellow and yucko pink. That was using the Quikrete cement dyes. Regarding swirling, I've never tried and you do have to watch out how much dye you use because the mix won't set up if you use too much dye. Maybe try a test stone with the swirling technique. Keep us posted. Billie

Billie - Yes, I'm making the garden art...glass totems, birdbaths and plate/glass flowers. When I made the concrete stepping stones last summer the smoothest ones are the ones I turned over to expose a design that was in the molds. I don't know why I mentioned lining the molds with plastic. Something I read on one site. Not sure what I'll put between stones. Maybe moss or other ground cover. Any ideas?

Yes, I realize that we have accomplished a lot and we're TIRED. My DH hates to have anybody help us so we've done all of it ourselves. We're getting too old for this.

Laura, My husband and I do most of the work around our house because you don't seem to get good quality work.
Speaking of totems, you can make hypertufa/mortar/concrete totems. If you do a search on this forum you'll find Eva's sand cast totems. I don't know if Eva still posts here but she does some wonderful work. Wylee use to post here too and made totems from grot heads. I think Eva's were birds or fish....I don't remember. You can also take various molds (plastic bowls-cups-planters), make your piece with a hole in the center and when cured thread them on a dowel standing upright in your garden.
Regarding what to put betweem your stepping stones, depends on the sunlight that their in. You can do moss in shade or low growing thyme in sun. There's also something I'm remembering called "steppables" and they were meant to be planted between stepping stones. Billie

That's amazing artwork! I hope the weather will stay warm here in W. Washington for a few months after we finish the landscaping so I'll have time to play around a little with hypertufa.