I went searching in the shed for the mold that I used before, but I couldn't find it. I didn't want to buy a new mold, so I improvised. For one stone, I used an old plastic bowl that I didn't use anymore (cause I left it outside after a cookout and never got around to taking it in). If you actually put your stuff away and don't have any old ones laying around, just go to the dollar store and get one. Its much cheaper than buying the "stepping stone mold" from the craft store. For the other stone, I used a cardboard box. .
Mix up some concrete and water to a brownie consistency. Then, pour it into your molds and smooth it out. Let it set for a couple of minutes, then let your kids decorate. I decided to do my kids footprints. In one, we used stones that I had left over out of an old vase of flowers. I don't have a picture of it, but for one I used stones left over out of an old fishtank. You could also use rocks from the yard, left-over nuts and washers, cut-up straws, just whatever you find laying around.
Another option, we had a bag of sand left-over from the sandbox, so I cut the top open and had the kids step in it. When they picked up their feet, their foot-print was left behind. So, I filled the footprint with mortar, let it hardened, and pulled the hardened form out. It made a foot-shaped stone.
Let your stone set-up about two days and there you have it! Between pouring in the ingredients, mixing it up, pouring into molds, adding embellishments, and stepping into wet concrete, my son loved this project!