All my brother wanted for Christmas was a secret door. Since every self respecting man should have one. I began by taking some measurements, doing some internet research and this is what I came up with. The hard part was that he lives an hour away from me. So I had to build a mock door frame, transport it and hope things matched up.

Step 1: The Build

Unfortunately I don't have many pictures of the build so I'll explain it the best I can.

Materials:
Sheet of 3/4" smooth plywood
Sheet of 1/2 plywood
Lazy susan
Long bolt and washers for top pivot point
Misc. trim /spacer wood
Rubber wheel 6"
Screws
Wood glue
Trim to match house
Gate latch with fishing string and special book for secret opener.

The Build
I begin by making a door frame to the exact measurements of my brothers closet. The dimensions of the finished door came out to be 34" wide, 77" tall and 8" deep. I assume if you are building this project you have enough wood working skills to make a bookshelf and your sizing will vary so I won't go into detail about that.

The door is a solid bookcase made from 3/4 smooth plywood and 1/2" regular plywood for the back. Glued and screwed on all sides. There are five attached shelves and adjustable shelf holes drilled at the top. I made a template to help drill the holes all the correct width and height.

One of the hardest parts was the hinge point. I used a lazy suzan on some 2x4 blocks for the bottom and a long bolt for the top. It took a lot of measuring and testing to get it centered right. Adequate spacing was needed on the hinge side to just barely clear the door frame and still be covered by trim.
Most commercial doors have steel frames and don't need caster wheels. Due to the weight of the shelves and contents we added a bed caster. Which needs to be changed because it's marking my brothers soft wood floors.
**Update. New 6 inch rubber wheel replacing bed caster, installed a little bit higher and hidden with fake books. It does not even hit the floor so I think this fixes the problem.

Step 2: Installation and Tweaking

Installation involved removing the closet door and trim. Screwing in some wood blocks to the inside wall that would accept the top hinge bolt.

Once the door was in place, I tested the opening many times and then secured the base with 4" screws.

The latch bolt was installed to the interior door frame matching the latch height. A fishing line was secured and run through the back of the door and connected to the secret book opener.
Hindsight note: Double or triple knot that fishing line or it might come off and your door is stuck closed.

The secret door opening book was a really nice touch supplied by my brother. I glued the pages together to make a solid area for attaching a small brass hinge and fishing line to pull open the latch.

Step 3: Finish

My brother finished painting and loading with books and decorations. I think it turned out really nice and I'm told it's a great conversation piece when company comes over and he puts their coats away.