How to Make Concrete Countertops With Embedded Decorations

Measure the length and width of the counter you're building the countertop for. Add three inches to each dimension. For instance, if you have a 48-inch wide counter that's 24 inches deep, your final numbers will be 51-by-27 inches.

Transfer the measurements to the 3/4-inch melamine board and cut out the base of the mold you are building. Cut sides for your mold that are 3 1/4 inches wide. Make the sides for the short ends 1 1/2 inches longer than the short sides of the mold base. Cut the sides for the long sides of the mold the same length as the long sides of the mold. For a 48-inch wide counter that's 24 inches deep, you will cut two 25 1/2-by-3 1/4 pieces and two 48-by-3 1/4-inch pieces.

Assemble the mold on a flat sturdy work surface. Screw the long sides into the mold base with 1 1/2-inch screws first, lining up the ends of the mold sides with the ends of the base and screwing through the mold side pieces into the edge of the mold base. Screw the short sides to both the base and to the ends of the long sides. Use one screw every 6 inches all the way around the mold. You now have a mold that's 2 1/2 inches deep.

Caulk all the seams with silicone caulk, smoothing the caulking with one finger. Attach the decorative items to the bottom of the mold with a thin layer of silicone caulk and allow it to dry. Position the decorative items so they are lying against the bottom of the mold. Use the decorative items sparingly so they have impact and don't make the concrete surface too busy. Once the caulk dries, spray the surface of the mold with silicone release agent.

Lay rebar around the edges but not touching the mold sides. Cut a piece of wire mesh to fit inside the rebar and attach it to the rebar with wire ties. Remove the reinforcement, keeping it intact. Take care not to disturb the decorative items.

Prepare the concrete and fill the mold one-half full. Replace the reinforcing rebar and mesh, pressing it slightly into the mold. Continue to pour concrete until you have filled the mold evenly. Smooth the top of the mold and allow the concrete to dry for four days in dry weather and five days in high humidity.

Disassemble the mold and flip it right side up; you will need several assistants to accomplish this task. Carefully remove the mold base from the top surface of the concrete counter. Sand the surface of the counter with 200-grit sandpaper, avoiding the decorative items. Remove the silicone from the decorative items.

Apply the concrete sealant according to manufacturer's instructions and allow it to dry before mounting it on the cabinets.