Concrete and cement are popular media for homemade moulds and sculptures. They are one of the easiest types of media to pour: You can make moulds for simple cement and concrete items like patio stones, decorative plaques and sculptures using something that is likely already in your own backyard. Just grab a shovel and head over to your sandbox to make concrete and cement moulds.
Fill the box with damp sand. You can wet the sand as you put it into the box or ahead of time. It should be sticky, but not muddy or slippery.
Level off the sand. It should be even with the top of the box. Use the trowel to make the sand perfectly smooth and level.
Press items into the sand. Keep them at least 4 inches apart from one another. Press them straight down into the sand. Make sure that the sand is simply compressing, not flowing over them. If if is, refill the hole and dampen the sand before trying again.
Use your hands to make freestyle moulds. You can dig tunnels or make shapes or impressions in the sand to fill with concrete. This is particularly useful when you are making aquarium rocks.
Use the moulds within 15 minutes. This will prevent the sand from drying out and losing the finer details of your work. Once the concrete or cement has set, you can rinse the sand off and start enjoying your piece of art.
If you are making aquarium rocks, allow them to cure for six to eight weeks before putting them in your aquarium. Otherwise, the cement or concrete will create problems with the water's pH.