Use a screwdriver to remove the door from the cabinet by unscrewing the hinges.
Measure the width, height and thickness of the cabinet door using a measuring tape. Record these measurements on a sheet of paper. If the front of your cabinet door is decorated with wood trim, record the thickness of the door and the trim as separate measurements.
Cut a piece of unfinished wood to the dimensions of the original cabinet door using a circular saw. If possible, use the same type of wood as the original cabinet door and try to match the thickness. If you cannot tell what type of wood was used for the original cabinet door, take the door to your local hardware store to see if the professionals there can identify it for you.
Select an unfinished wood trim as close to identical as possible to the trim used on the original cabinet doors. If your original cabinet doors are not framed with trim, skip this step.
Cut four pieces of the wooden trim -- two to the width of the cabinet and two to the height. Trim both ends of each piece of wood at a 45-degree angle using a miter saw.
Apply a bead of wood glue to the back of each piece of trim. Arrange the four pieces of trim on the front of the new cabinet door. The angled cuts at either end of the pieces of trim should fit snugly together.
Secure the trim in place by driving nails from a nail gun through the trim into the cabinet door.
Fill the nail holes with wood filler and allow it to dry completely. Sand the dried wood filler smooth using fine-grain sandpaper. Go over the rest of the cabinet door's surface with the sandpaper to remove any imperfections.
Apply thin coats of wood stain to the finished cabinet door using a paintbrush. Wipe away the excess stain between coats using a clean cloth. Continue to apply layers of stain until the color of your new cabinet door matches that of the original door.
Install your duplicate cabinet door by attaching metal hinges along one edge of the door. Measure to find the position of the hinges on the original door and install the hinges on the new door at the same interval. Screw the other side of each hinge into the cabinet frame to attach the door.