Measure the length and width of each cabinet. Purchase new pieces of molding the same length and width as each cabinet.
Open each cabinet door and locate the hinges inside. Unscrew the hinge flap that sits on the inside of the cabinet and the inside of the door. Remove the hinges from each door. Set the screws and hinges in a safe location.
Cut a 45-degree angle in the end of each molding piece. The angled ends let the pieces fit together on the cabinet doors without any overhang.
Arrange the molding pieces on top of the cabinet doors. Push each molding piece so that it sits flush with the bottom edge and not the top bevel. Each cabinet door should have four pieces of molding that create a frame on the top of the door.
Attach the molding to the cabinets with a nail gun. Hold the nail gun flat against the top of the molding and press down, sending a nail through the molding and into the cabinet. Attach the nails every two inches across the molding.
Cover the top of the nails with a small piece of wood putty. Wood putty has a thick consistency that molds to wood surfaces, like the molding. After the putty dries, sand the excess with fine-grit sandpaper.
Paint the cabinets and molding. After the first coat dries, apply a second coat if you like.
Hang the doors back on the cabinets with the original hinges and screws once the paint is completely dry and no longer tacky.