Set down six 1-5/8-by-6-by-45-inch boards with their long, thin sides against each other in a 36-by-50-inch rectangle. Set two 1/2-by-3-by-34-inch boards perpendicular to these boards, evenly spaced on top of them with their large sides together.
Drill two holes through each 24-inch board and into each 50-inch board for a total of 24 holes, being careful to drill through the larger boards completely. Attach the boards together with 2-inch wood screws.
Repeat this process with six 1 5/8-by-6-by-35-inch boards and two more 1/2-by-3-by-34-inch boards to create a 36-by-30-inch panel.
Hold both panels up against the doorframe using the help of assistants and placing the larger panel above the smaller. Keep the panels about 1/8 inch apart and position two evenly-spaced door hinges between the frame and each panel. Mark the attachment screw holes for each hinge. Drill holes into the door and frame for each hinge. Attach the hinges to the door and frame with 1 1/2-inch wood screws.
Position a doorknob on the bottom panel of the door against the opposite edge of the door from the hinges. Mark the spot where the bolt should go through. Drill out the hole for the doorknob. Drill another hole through the edge of the door and into the previous hole. Attach the doorknob to the holes in the door.
Position a deadbolt between the two sections of the door so that the sliding latch portion is on the top panel of the door. Mark the attachment screw holes for the deadbolt. Drill out each hole and attach the deadbolt to both panels with 1-1/2-inch wood screws.