Often items that need to be stored are small and sometimes it is hard to locate them on storage shelves because they become hidden behind larger items. Usually, there is an area behind a doorway that is wasted. This space gives an opportunity to build storage shelves that are narrow, and create a place for those small items. In addition, the storage is hidden until you look behind the door.

Step 1: Requirements

Plywood or natural wood 5/8 inch
Shelf supports (homemade or bought)
Corner brace (to anchor the top of the shelves to the wall)
Nails or screws (suitable for the dimension of the wood)
Paint (if you intend to paint the shelves)

Step 2: Building the Shelf: Step by Step

Measure the space between the wall and the hinge of the door where you plan to build your shelf. This will give you the maximum depth of the shelves. Its helpful if the shelves are made the same width as the door so that the shelves are completely hidden when the door is open.
Decide on the finished dimensions of your shelf.
Cut your wood to the depth of your wall space (my shelf was 4" deep).
Then, cut two pieces the width of your shelf (this will be the top and bottom panels).
Cut two more pieces the final height of your shelf, minus two times the thickness of your wood or 1 1/4". These will be the side panels of your frame (2 x 5/8" - the side panels sit between the top and bottom panels of your shelf).

Next you need to decide how many shelves you want.

Measure the height of the items to be stored. Take this measurement and add the thickness of the wood. This will give you a height for each of your shelves (they may all end up being different heights). Calculate how many shelves of the various heights you can fit into your frame.
Next you will cut your shelves. The shelves fit inside your frame and are screwed together from the outside. Measure the inside dimension of the frame to figure out the length of your shelves, and cut out however many shelves you need that length.

Now its time to put it all together.

Screw the top and bottom panels to the side panels from the outside. Mark the position for each shelf and then screw it to the frame. For additional shelf support, you can cut up small triangular pieces of wood or molding, and add them under the ends of each shelf.

Finally, you can finish the wood however you choose or leave it plain.