Measure the width, depth and height of the television and stand with a measuring tape.
Measure six pieces of 5/8-inch-thick plywood 2 inches larger than the dimensions of the television and stand. These sections form the bottom, top, sides, front and back of the stand. Cut these sections to size with an adjustable table saw.
Adjust the table saw blade to a 45-degree angle. Miter the edges of the enclosure sections.
Stand the back and sides along the edges of the bottom section. Drill pilot holes through the sides and back into the bottom at 4-inch intervals. Insert 4-inch wood screws through the pilot holes with an electric screwdriver.
Drill pilot holes through the sides into the back of the enclosure at 45-degree angles. Insert 4-inch wood screws into the pilot holes.
Place the top section of the enclosure on the sides and back. Drill pilot holes through the top into the edges of the sides and back at 4-inch intervals. Insert 4-inch wood screws to secure the enclosure top.
Equip a drill with a 1-inch paddle bit. Drill a hole through the back of the enclosure near the bottom for cables and electrical cords.
Install metal hinges about 2 inches from the top and bottom of the inside part of the door. Install the hinges on the inside of the enclosure. Install a magnetic latch on the opposite side of the door and enclosure.
Use a utility knife to cut sections of waterproof weather strips to fit the inside edges of the door. Peel the backing from the weather strips and install them along the door's inside edges.
Use a paintbrush to apply a coat of waterproof sealant to the exterior of the enclosure. Allow the sealant to dry for one hour, then apply a second coat.
Apply waterproof caulk along the seams to prevent moisture from entering the enclosure.