Here is a step-by-step tutorial on how to make concrete countertops:

1. Build the Mold: To determine the size of your countertop, measure the base cabinets that the countertop will be sitting upon. Add an extra 3/4" for each overhang. Cut the sides of the mold.

2. Make Cutouts: Cut out the sink and faucet holes using a jigsaw.

3. Build Support Frame and Prep Wire: Build a support frame out of 2x4s to hold the weight of the concrete. Add wire mesh for reinforcement.

4. Mix and Pour Concrete: Mix concrete according to instructions and pour it into the mold.

5. Remove the Mold: After 24 hours, remove the mold.

6. Finish the Slab: Sand down any rough spots and fill in any holes with concrete filler.

7. Install the Countertop: Seal the countertop with a food-safe sealer and install it on top of your base cabinets.