NOTE: Use the plywood off-cut from the door opening in the wall to make the door. Re-trim the edges of the plywood off-cut so that it is at least 10mm (3/8") smaller than the door opening all the way around.
Nail 150mm (6") long metal straps (or similar type fasteners) to the top and bottom of the door (4 pieces in all) securing the top and bottom horizontal members to the side vertical members.
Also ensure that there is at least a 10mm (3/8") gap between the wall battens around the door opening and the finished door. (See drawing i)