You can build built in cabinets around a fireplace by following these simple steps: 1. Measure the dimensions of your fireplace opening. 2. Cut two pieces of plywood to those dimensions. 3. Screw the plywood pieces together to form a cabinet frame. 4. Cut cabinet doors and drawer fronts from additional plywood and attach them to the cabinet frame with hinges and screws. 5. Sand and paint or stain the cabinet frame and doors as desired. 6. Install the cabinet frame around your fireplace opening, using screws or nails to secure it in place.

There are many ways to build cabinets around a fireplace. The most common way is to measure the width of the opening and build your cabinet to that size. You will also need to measure the height of the opening and then build your cabinet to that size as well. If you want your cabinets to be flush with the fireplace, you will need to take into account the thickness of the mantel. Most mantels are about 2-3 inches thick, so you will need to add that measurement into your calculations. Once you have all of your measurements, it's time to start building! Be sure to use a level when you're measuring and building in order ensure that your cabinets are straight and even.