Place the 1/2-by-3-by-17-inch boards parallel to each other on a work surface. Orient the boards horizontally with the 1/2-by-17-inch side flat on the work surface. Space the outside edges of the boards 24 inches apart. These are the top and bottom boards.
Butt the 1/2-by-3-by-24-inch boards up against the ends of the top and bottom boards to form a rectangular assembly. The 3-by-24-inch sides should be flush against the ends.
Drive two evenly spaced wood decorative wood screws through the sides into the ends of the top and bottom boards using a screw gun.
Lay the 1/2-by-8-by-18-inch board across the bottom of the rectangular assembly. The 8-by-18-inch side should rest flat on top of the assembly. The bottom 18-inch edge should be flush with the bottom edge of the bottom board. This is the lip for the rack and it holds the contents of the rack in place. Drive decorative wood screws through the lip board into the edges of the assembly every 2 to 4 inches using a screw gun.
Turn the assembly over. Lay the 1/4-inch plywood panel over the assembly so that the edges line up flush with the outside edges of the assembly. Hammer finish nails through the plywood panel into the edges of the assembly every 2 to 4 inches. This is the back of the rack.
Drill two holes through the back of the rack. Locate the holes 2 inches down from the top edge and 2 inches in from each side. Use a drill equipped with a 1/8-inch drill bit. These are the mounting holes.
Center the rack assembly on the inside of the pantry door. Drive a decorative wood screw though each mounting hole into the the door with a screw gun to mount the rack on the pantry door.