Introduction: Super SIMPLE Secret Bookshelf Door & Book Unlock Mechanism

About: I enjoy coming up with ideas for things and then trying to build them. It brings me pleasure.

Much like, I imagine, every child who read comics or watched Batman or any of the numerous literary or pop-culture examples of secret doors leading to a Bat-Cave or secret passage/room, I've dreamt of having my own secret door hidden by a bookshelf. I mean, who wouldn't?

Here's the thing, I am not a carpenter, electronics wizard, nor do I live in a Bruce Wayne mansion (I don't have a wood shop or even a work station, I have two bags of various tools), oh, yeah, and I live in NYC so space is not abundant. BUT, if I set my mind to something, I usually end up figuring out a way to make it work. This is an Instructable on turning ANY regular door on the wall into a Secret Bookshelf Door that hides what is behind it.

The General Concept: Turn a regular door on the wall that opens out into the room into a hidden door by building a floor-to-ceiling bookshelf that has the width of just larger than the door frame (I will explain why "just larger"), where the bottom section of the bookshelf (that covers the door) can open when unlocked.

(1) Make the bookshelf look like a bookshelf when it is closed, and
(2) Make the lock/unlock mechanism a book that is pushed in within the bookshelf.

NB: I have learned some valuable things from the few Instructables I have posted and just in general with building stuff:
(1) Wear and use proper safety protection! I cannot stress more the need to stay safe. Yes, you are great with a router or a drill, but let's see you move faster than the Flash to avoid a minuscule piece of wood that chips off and flies at your eye at insanely fast speeds.
(2) Protect surfaces ... if you are dealing with a wood floor, it is always good to cover it with protection so you do not scrape it.
(3) Do not overfill a fish tank with too many fish for the space! Now, I know this Instructable does not have a tank or goldfish or fish at all, or even water, but I've found that those who read Instructables, in general, really get mad if you have too many goldfish to proper water ratio. So be aware.

Pictures in this section: Original door, finished door (closed & open)

[I am entering this Instructable into the PROTECTED CONTEST ... if you like this Instructable, please please VOTE for it! Thank you ahead of time, and enjoy!]

Step 1: Take Off Door and Door Trim & Fix Any Structural Issues

First things first, you need to remove the door* and any door trim so as to create a smooth surface to make it look like the bookshelf is directly against the wall. *If you already have a solid door and appropriate hinges to support the weight, then you do not need to remove the door. I had a hollow wood door and two sub-par hinges that would not hold weight. Remove the door by unscrewing the screws on the hinges that anchor them to the door frame.

I used a box cutter to remove the caulk and then gently pried off the trim (with a flathead screwdriver and hammer). What I found was a wonderful mess. Instead of the door frame being anchored to studs, there were shims in place with screws driving the door frame into the studs a distance away. The other great contractor work that was left me was that the spaces between door frame and studs were all different depending on the side. I measured the appropriate gap for each area (left, top, right), bought and cut wood to length, and then removed the screws on the door frame, removed the shims, and replaced the gaps with solid wood pieces, screwing in 2.5" screws to secure the door frame firmly to the studs ... this door is going to hold some weight so it needs to be properly anchored into weight-bearing structures.

After fully securing the door frame, I used Ready-Patch to fill any gaps and create a smooth wall surface. It took a few layers of patch as there was much to smooth.

At this time, I also removed the molding on the bottom of the wall. They were old and I wanted to fully cut to size new molding to match later.

Step 2: Put Up the New Door & Hinges

Since this door was going to have to hold a bookshelf full of books, I bought a solid wood door and 3 heavy duty ball-bearing hinges (ball-bearing hinges are a smoother open and close and, to my understanding, are good at holding weight).

This was my first time installing hinges and a door ... so things to note:
(1) Measure, measure, measure!
(2) Don't cut too deep into your door frame or your door to place the hinges, they must be FLUSH, and not inset, or the door will not fully close!
(3) ALWAYS pre-drill holes for your screws so that when you screw in to wood it does not split ... the holes you drill should be just slightly smaller than your screw so that the threads have something to fully catch onto.

Okay, so I went online and researched the different distances from the top and bottom of a door to place hinges, and ended up going with the top hinge being placed 7 inches from the top of the door and the bottom hinge being placed 11 inches from the bottom of the door, and the middle hinge in the middle of the top and bottom hinges. There are different arguments for positioning for weight-bearing, and this seemed to be the most prevalent. I am sure this is a debatable subject, but I went with what seemed to make the most sense.

I measured on the door first, drilled a couple of pre-screw holes, then put in a couple of screws on the hinges, marked the edges with a blade, then removed the hinges and dug out the space using a hand chisel and a Dremel to smooth the internal surface. I then placed the hinge in the groove and screwed them into place. The fun thing about ball-bearing hinges is that you cannot take them apart to put them on the door. So what I did was I stood up the door with the hinges on it, and propped it up about 1/4" from the ground using wood pieces I had from fixing the door frame. From there, I measured the exact place of the hinges on the door frame and outlined them with a pencil. From there, I laid the door back down on the ground and chiseled/prepared the door frame for the hinges. Once prepared, I lifted up the door and attached it to the door frame. Ta da! New solid wood door is up and functional!

NB: Since I am a newbie at this type of work, I ran into issues with above #2 and had to modify the door slightly because my depths were slightly off. Additionally, it turns out that the person who built the door frame in the first place decided to build it different than normal door specs, so I had to shave the top/bottom, and one side down a little to have the door properly fit in the door frame. Not the end of the world, but annoying.

Step 3: Build Your Bookshelf!

The next step is building the bookshelf that will go over your door.

I measured the height and width meticulously (see pictures of handwritten diagrams of everything), and decided on a height for each shelf (I used the height of books I had as reference). The design includes a space at the bottom of the bookshelf to fit support wheels, and small lips on each shelf to keep all books secure. Additionally, the door part of the bookshelf has the height of the top shelf's books reaching over the top of the door--this way books on that top shelf would cover the top of the door and hide any traces of the door opening, especially if a light was on inside the room. Equally so, the shelving width is 1/4" wider than the door as to hide the connection point to the wall when closed (reaches over on the non-hinge side).

To build the bookshelf I attached the bookshelf sides together temporarily.

I measured the shelf heights (10.75") and added the shelf thicknesses, starting up 2" for the bottom [leaving the space for the wheels].

I marked each side (top and bottom) where the shelves would be -- I decided on dado slots as to make the shelves more sturdy and secure. You lose the ability to adjust shelf heights but I wanted to make sure the shelves would hold book weight and also not slide around when the door was opened and closed.

I placed tape (started with some gaffers I had and moved to electrical when I ran out -- gaffers = good, electrical = not good) above and below where the dado slots would be, the tape was a guide and reduced any splintering.

NB: Dado slots are when you clear a depth in a shelf wall that the shelf can then slide into. With added wood glue and screws through the shelf sides, it adds superior weight bearing and structural stability compared to most other methods.

I then used my Dremel with a routing attachment, adjusted it to the correct length (I did 1/2 inch first and then adjusted to 5/8 inch for just one side to accommodate the extension beyond the side of the door). I had to do a few passes and broke one routing bit. I then used a hand chisel and the Dremel sanding tool to make the slots clean.

NB: The advantage of attaching the two bookshelf sides together for this process allows me to make sure the dado slots on both sides of the shelf are cut to the same height. (That said, when your floor is not exactly level, and you find that out only after creating a level system, you have to make some adjustments.)

Once routed, I checked to make sure each shelf fit in the dado slots, then added wood glue and placed in the "wire" nails I bought to keep alignment with the shelves while I drilled pilot holes for the screws, and then screwed the shelves in from the side with 2-inch screws.

I then checked the placement of the bookshelf on the door to make sure the wheels fit properly and everything aligned. Of course, my floor was not level so I had to shave a couple things, but hopefully, if you try this, you won't have as poor an original contractor on your space.

Once ready for the door, I attached the wheels to the bottom of the shelf (I used two tri-wheels I bought at Home Depot and affixed them to the outside and the middle of the bottom of the door [the hinge side will have the hinge holding weight, so the far side will be much better for placement and weight-bearing]). I measured and placed the wheels so that they would NOT be touching the ground during usage, and only if the hinges could not hold the weight properly would they come into play and carry weight with a slightly sagged door (something like between 1/16th inch off the ground). Ideally, the door opened and closed without the sound of wheels on the floor -- also would keep the floor more protected. As it turned out, the hinges are strong and the wheels have not been needed as of yet.

NB: A helpful tip I learned on set for plugging in to extension cords is to tie the two connecting ends in a loose knot first, this way, if one cord gets snagged/pulled, it tightens the connection and stays together instead of pulling apart or half pulling apart and opening you up to potential electrical issues!

This is the basis for the shelf that goes over the door. Next you will attach the unit to the door.

Step 4: Attach Shelf to the Door & Make It a Little Pretty

First, since my door opens out, the slight give-away for the hidden door are the exterior hinges. So, after placing a 1/8th inch piece of wood propping up the shelf to a respectable height, I measured the location of the hinges on the shelves and then cut a depth out to cover the half of the hinges that when inset will blend pretty well with the side of the door. Measure, cut, sand, and make sure it fits ... or sand and make sure it fits, again.

I got a whole bunch (2 for each shelf) large L-brackets and drilled partial pilot holes (always drill pilot holes when screwing into wood to ensure you never split it by accident) and then screwed in 1.25-inch screws from bracket to shelf and then bracket to door. The goal was to place the brackets under each shelf so that along with attaching the bookshelf to the door itself, the brackets could take the weight of the shelves right above additionally, to distribute the weight even more evenly across the door. I placed brackets under the top shelf and then used wood filler to fill in the places where the wood pieces met, and to cover the screw holes and nails on the sides of the bookshelf (this way painting would be more seamless).

After the wood filler dried, I sanded to make it all nice.

I then added the rest of the brackets under each shelf, and under the shelf with the wheels -- I'd recommend prepping these bottom-most brackets before putting the shelf on the wall...or having a really looooong screw driver available.

Now to make a little sleeker...

Measure distance between shelves (22 and 3/8ths inches, in my case) and cut a lip for each shelf -- I used a one-quarter of a circle with 1/2 inch radius wood rod (there is likely a technical term for this, I'm not sure what it is. It looked like what I wanted at the lumber/hardware store). I used my thin nails and nailed up from the bottom of each shelf, applied wood glue to the top, and placed the lips in and nailed up from below. At this point, to match the bottom of the shelf with the molding I was replacing on the bottom of the wall that I had removed, I cut to match molding to cover the space where the wheels were hidden and nailed the molding to the bookshelf bottom...the bottom molding reaches up and is a guard for the bottom-most shelf.

I added wood filler to these new additions, and then sanded.

Shelf is now on the door. You are getting close!

Step 5: Prepare Top Shelf

Now that we have the shelf on the door, the shelf attached to the wall above the door completes our illusion.

Again, after meticulously measuring, cut dado slots the same as with the larger shelving unit created earlier, and place over door shelving system. In my case, realize that the wall is neither vertically nor horizontally level and make adjustments as best as possible.

Place cardboard between the bottom shelf with the top wall shelf to make sure there is no friction, and then attach the top shelf to the wall. I used drywall anchors to make sure weight was not an issue, and located the stud in the wall and made sure to add an additional bracket into the stud for the upper shelf.

There is a small gap between the the shelves, but once stained with a darker paint (so painted, not stained, I know, but that is what came to mind), the gap will not be noticeable.

Admire your work, since this took you way longer than you were expecting and your significant other has been waiting for the piles of tools and wood to get off your living room floor for way too long. [Possibly play Europe's "Final Countdown" at this time, but you can also wait until after the painting is done because it looks even cooler then. ... or just have it playing on repeat the whole time.]

Step 6: Put in Magnetic Lock & Paint This Thing!

For a hidden bookshelf door, there MUST be a secret book that unlocks and opens the door. It is a fact. The first step in this process is a super secret lock. I bought a kid safety magnetic lock -- the "Safety 1st Tot-Lok Starter Set" ( The key to this lock is that it was created for keeping cabinets from being opened by children so they would not get into chemicals under the sink or the like. How the lock works is that it has a locking mechanism that has a metal rod at its base, and when activated by the accompanying magnetic handle (that is placed on the outside of a cabinet), the locking mechanism is triggered, and opens. Since the solid door is decently thick, I had to modify the lock. I attached the lock latch to the inside of the door frame, and then, using the map that comes with the lock, drilled a hole through the door to add extension metal rods to the locking mechanism to extend its reach (the extension rods come with the lock). The lock comes with a plastic piece you put over your drill bit to tell you when to stop drilling -- you want to drill as deep as possible without actually drilling all the way through the wood. In addition, I added a few rare earth metal magnets to the end of the magnetic handle to ensure unlocking occurred through the heavy wood that is the door. I tested it multiple times, and was very happy. [More on this when I explain how to create the book that unlocks the door. Yes, I said the book that unlocks the door, you read right.]

Painting -- I first used painters tape and covered the interior of the shelves and painted the door and back bracket parts to match the color of the wall behind it. I also painted the interior sides of the door so that any seams would look to blend into the wall even if noticed. Once dried, I removed the tape and taped every other area in preparation to paint the full shelf.

I used an espresso color, to match other shelves we have in the apartment, and painted the shelves with a couple of coats of paint. I also painted the top of the bottom shelf and the bottoms of the top shelf (so when the door is open there is nothing unpainted). I think it came out quite well.

Play "Final Countdown" (again) while opening and closing the door with the magnetic handle while giggling to yourself at your genius.


A super secret hidden door bookshelf cannot be opened by a simple lock and cannot have a simple handle, pisha I say to that! For a bookshelf door, one needs a book to unlock it.

NB: For a design that involves the same embedded magnetic handle but pushing the book/sliding the book into the bookshelf to unlock, see my initial sketches. Since the initial push unlock involves springs and a guide rail to be placed and hidden, I decided on the hinge route to keep things simpler. [I have learned that the more complex a solution, the more ways it can have issues to be fixed in the future.] The small hinge route allows me to change the book easily if I want.

First, measure the depth and height of your shelf (the one that is approximate waist height or 3 feet [36 inches] from the ground). The key is that you want to choose a book that is not too high so that it cannot be tilted backwards fully, but not too short so that one can see over the top of the book to the back, which could destroy the illusion, possibly. ALSO, and this is key, the book you choose must also have significant meaning so as to impress those who realize that it is the book that opens the hidden door. My current book is "Question Time" (the answer to the "question" is that it is a key, hey-oh!). This book resides next to "Hide in Plain Sight" and "The Adventure Girls," among others. [Though a friend just gave me "The Key to Magic" book, which is even more perfect.]

Once the book is chosen, you need to prepare it --

I measured approximately where on the book (when on the shelf) the magnetic handle would have to be, and marked the book appropriately. I then did 2 things: (1) Used a box cutter to cut out a space in the book that would fit the handle [which will be placed at an angle later], and (2) I used a hand file and filed down the sides of the magnetic handle so it would fit snuggly in my book and would also allow the placement of the magnetic end of the handle to be closer to the side of the bookshelf and exactly over the embedded metal piece within the door. You can also glue the earth metal magnets to the handle if not done so already.

And then, much like creating a secret compartment in a book, you mix Elmer's glue with a little bit of water and then paint the outside pages of the book while it is closed. The water helps dilute the glue and allows the book's pages to absorb the adhesive more and thus penetrate deeper into the pages, for a stronger hold. Elmer's glue dries clear so you cannot see a visual difference ... it looks like the original book except that the pages now stay as one ... please remember NOT to glue the top cover down with all the rest of the pages. If that happens, the next step might be a bit difficult.

Let the book dry and repeat with a second coat of glue for safety. What I then did, once all dry, was screw in the side of one small hinge I had. Because the pages are now sealed and glue absorbed, the screws screw right in. I added some super glue after they were in for added strength.

Once hinge was in, I placed the book on the shelf and (1) marked where I would need to drill pilot holes in the shelf for the other side of the hinge, and also placed the handle against the door for it to unlock and marked on the inside of the new book compartment exactly where I needed to attach the handle.

I then superglued in the handle to the book and let it dry. And while the handle and book dried, I took the hinge apart (a pin came out and allowed the two sides of the hinge to separate) and screwed in the shelf-side part of the hinge. Once the book was fully dried, I joined the hinge pieces, put the pin back in and ... voila!!! And by "voila!" I mean, WE NOW HAVE A BOOK THAT OPENS A HIDDEN DOOR BY TILTING BACK!!! Booyah!

Step 8: Replace the Moldings

I then cut the molding that I bought to match the spaces on the sides of the bookshelf, filed down one edge of each to fit with the molding at the edge corner of each side, and adhered them to the wall with some crazy strong adhesive material. I then pushed my tool bag and a complete works of Shakespeare book against each molding, respectively, and let them dry.

At this time, I also took the opportunity to buy a brown permanent marker (well, my fiancee bought it for me, technically), and colored in any color gaps on the hinges on the side of the bookshelf so that they blend in 100% [with the opening and closing of the door, some of the paint that I had painted on the hinges rubbed off ... permanent marker does not rub's permanent.-ish.].

Step 9: Admire Your Work!

Books tilts and works!

Add books and whatever you want and then make a video of the bookshelf and spend way too long typing up your full Instructable:

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