Use the stud finder to locate two adjacent studs in the area you want to put the cabinet. Mark their locations with the marker.
Place the cabinet door onto the wall, between the lines that mark the locations of the studs. Draw lines on the wall at the top and bottom of the door.
Cut the drywall at the lines you drew, using a utility knife. Pull the section that you cut out of the wall.
Place the door on top of the plywood veneer. Trace an outline of the door on it. Cut this rectangle out of the larger piece of veneer.
Apply a thin layer of glue to the back of the niche that you made in the wall. Press the veneer piece onto the glue and allow it to dry.
Screw two angle brackets into the stud on the left hand side of the niche, so that they sit level with the bottom. Do the same on the right.
Cut three pieces of wood from the plank. Make each piece as long as the distance between the studs. These are the shelves for the cabinet.
Coat the two short ends of one of the shelves with glue, and one of the long sides. Set this shelf on the brackets so that the glue adheres to the studs and the back of the niche. The brackets support the shelf, and the glue keeps it from slipping or being knocked out of place.
Divide the height of the niche by three. Make a mark on the studs inside the niche at one-third and two-thirds the height of the niche.
Screw two more angle brackets ¾ inches below each of these lines. Set the remaining shelves on the brackets, gluing them in place in the same manner as the first shelf.
Screw the hinges onto the cabinet door. Hang the door on one of the studs by screwing the other sides of the hinges to it. Make sure that the door is placed so that it completely covers the cabinet. Screw the latch hardware onto the other stud, in accordance with the manufacturer’s instructions.
Stain and/or varnish the cabinet, inside and out, to fit your décor. Allow it to fully dry before putting things in the cabinet.