Martha Stewart Living, September 2000
Trim the bottom or top of the door so the rails (the ladderlike crosspieces that separate the door's panels) are equal in width; on most old doors, the bottom rail is thicker than the others. A standard-height door will be tall enough for any size bed; trim as needed.
Sand, prime, and paint the door.
To mount the headboard, cut a 1-by-4 to the headboard's width, and then cut it lengthwise on a 45-degree angle into two equal strips. Securely screw one strip to the back of the door and attach the second to the wall, so the angles interlock to hang the headboard.
Keep the bottom of the headboard the same distance from the wall by screwing a 1-inch-thick strip to the back.
Finish the top of the headboard by nailing on a mitered crown molding.
Primer and paint
Mitered crown molding
Check yard sales and flea markets for doors, and modify the steps below if you find one with a different design. A strip of crown molding along the top edge offers a neat finish and a handy spot for a small alarm clock.