Lay the coat rack on a work table and draw two pencil marks to indicate the locations of the hanging holes. The best locations are on the inside of the pegs on either end. Use a tape measure to determine the center point between the pegs for aesthetic purposes. If the coat rack already has holes, skip this step.
Don safety glasses and drill holes in the coat rack using a 1/4-inch bit and a drill. Use a standard wood bit for wood racks and a cobalt bit for metal coat racks.
Locate the hinges on the metal door and insert a nail set or a screwdriver shaft in the bottom to dislodge the hinge pins. Set the pins aside and lift the door free from the frame. Place the door on top of two sawhorses.
Hold the coat rack up to the metal door until it is in the desired position. Insert a pencil through each hanging hole to transfer a mark to the door. Set the coat rack aside.
Insert a nail set tool or the tip of a metal nail on one pencil mark. Tap the head of the nail firmly with a hammer to create a dent in the door. Repeat the process on the other pencil mark. These indentations help prevent the drill bit from sliding.
Insert a 1/4-inch-diameter cobalt drill bit into a drill if one is not not already installed. Place the tip of the bit in one of the indentations and squeeze the trigger to drill a hole until you penetrate the door or puncture the inner hollow cavity. Repeat the process on the other indention.
Place the coat rack back on the door and align the holes with those in the metal door. Insert a 1/4-inch sheet metal screw through each hole using a power drill.
Rehang the metal door in the jamb by aligning the hinges and inserting the pins in each.