Pocketex: the Miniscule Cryptex




Introduction: Pocketex: the Miniscule Cryptex

This Instructable takes Da Vinci's cryptex to a miniature level.

The basic premise of the cryptex is that it allows the creator to hide a secret within the capsule and lock it using a simple slotted key mechanism. A password aligned perfectly with the arrow is the only way to unlock the cryptex. Or you could smash it to pieces. The password is entered using a series of dials that spin around the canister and allow the key to be released.

The fundamental components of a cryptex are its key, dials and canister. You could make one from scratch and there are instructions to do so, but if you want to fit this thing in your pocket, I have just the solution: a lip balm tube; specifically Nivea.

Step 1: Materials

List of Materials:

> Foam board 5mm [20x20cm board is sufficient]
> Thin cardboard
> Pencil
> Ruler
> Xacto knife
> Glue gun
> Cutting board

> Nivea lip care

Step 2: The Canister

The key must slide through a slot in the canister; the slot should be 5 mm wide and span the entire tube. Use the cap of the lip balm as the canister and use either a sharp knife or exacto-blade to cut the slot.

Try to keep the slot as straight as possible in order for the key to slide smoothly through it. The genius of this particular cryptex is that the fundamentals of the device is already done since we have sliding tube system in tact at this stage.

Step 3: The Key Prep

Assuming you already had the Nivea Lip Care before you decided to convert it to an ancient secret holding device, the next step would be to clean out all of the lip balm from the tube.

If you bought a new one specifically for this purpose, like myself, simply cut out the lip balm stick and wash out the insides of the tube.

Step 4: The Layout

For this step, you will need the sheet of foam board to make the rings for the dials and spacers. You will need to make 3 dials and 4 spacers. Essentially, we are going to cut foam strips and score one side of them to allow wrapping around the canister. Then, using cardboard, we will cut similar strips and glue them around the foam to create the writing surface for the letters.

Dial: Make 3 strips, 1.0cm wide using foam board. Score the foam along the horizontal lines and curve. Cut 3 strips, 1.0cm wide using cardboard. Score lightly along the horizontal lines and curve.

Spacers: Same as above, but make 4 spacers, each 0.5cm wide.

Step 5: Form the Dials

The method to create freely turning dials is to wedge them between the spacers. The spacers will be glued to the canister and the dials will be free to turn.

The foam rings were dimensioned so that they would not fully surround the canister. The idea here is to keep the slot in the canister free for the key to slide through. To do this, glue the foam spacer strip around the canister, leaving the slot uncovered. Trim the foam ring to fit. [Picture 1]

Next, glue the cardboard strip around the foam ring. This will hide the gap in the foam ring and will completely surround the canister. [Picture 2]

Now create the same ring using a strip for the dial. This time do NOT glue this to the canister, but have it free-turning. It should just slide onto the canister. [Picture 3 & 4]

Repeat the above steps by alternating spacer and dial until you have covered the whole tube. Keep in mind that the cardboard around the dials are used to write the password letters on. Make sure the gap in the foam ring is lined up with a cardboard surfaces. These particular surfaces are the key code when lined up so make a small mark on them so you remember which ones they are.

Step 6: The Key

The cryptex is locked when the keys are stuck between the dials when the wrong password is entered. In this stage, the key knobs are sitting in the gaps in the spacers. Therefore, the first step is to mark down where the spacers are on the key.

To make the key shaft similar to the canister, I added a foam ring to the handle in the same way as we make the dials. [Picture 2]

1> Line up the key and the canister and mark down where the first 3 spacers are. [Picture 1]
2> Cut-out 3 small square pieces of foam board, about 0.4 cm across.
3> Glue these 3 pieces on the key shaft in a straight LINE. This is very important. {Picture 3]
4> Key complete

Step 7: Stylize

Once your key and canister are completed, line up your marked dials and insert the key. It should slide in with no obstructions. Try turning the dials to make sure there is no interference with the key. [Picture 2]

Now it's time to think of a code word. It could be arbitrary or the answer to some riddle or a logical puzzle in itself. This cryptex uses the word 'SKY' for its unlocking. There are not enough spaces to write the whole alphabet on the dials, so randomize the characters around the ring. [Picture 1]

Cut a circle out of cardboard to cap off the end of the cryptex. This will hide the last spacer. [Picture 3]

Make a small arrow > to mark off where the codeword has to line up. This arrow must be exactly in like with the slot in the canister. Add some decals or whatever you like to fancy up your cryptex. [Picture 4]

Step 8: The Secret

Your cryptex is not complete until it serves its purpose to enclose a secret or gift only those worthy enough to solve the riddle can have access to.

Whether it be a message, some tic tacs, or even a pack of matches, it's entirely up to you. The neat thing about using a lip balm tube is that when you turn the bottom knob, the contents will pop out.

Et voila... with a bit of glue, some foam and a bit of da vinci genius, I bring you the Pocketex: the miniscule cryptex.

Here's a much larger one made using cardboard tubes, foam board and 4 dials. [Picture 2]


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    51 Discussions

    is the third letter needed to be solved? the inner tube when layed next to the outer tube in one of the images does not look long enough to have a knob added to it to fit up in the very last spacer just behind the third letter wheel. does that the last one does not work? or was it just a badly framed image?

    Great design its really cool but since its foam and card board don't you think its a little weak some one could just tear it open I'm not saying its terrible but maybe some stronger ingredients needed to make this awesome little project
    -really nice work

    I made mine out of a lipstick tube, a mouse pad, and some card board :)

    you know that gives me an idea what if you made a cryptex that would only open in a certain location (via a bolted down "key") so that even if you knew the combination it still wouldn't open

    16 replies

    someone did that using an arduino, gps sheild, and alot of electronics.  it had a clue and told you how far you are from the location but not the direction.  it had a fail safe that can only be opened when the batteries where dead, which was unlikely since it was run on a solar cell and a backup battery.

    by clue that told you how far you are from the location, i meant a clue that tells you where it would open and an lcd screen that told you how far you are from the location but not the direction.  and the failsafe was only to replace the batteries.

    it opened in the louvre because the owner was moving closer to a freind to work at the louvre

    couldn't you just use a lock box then? or a slightly modified lockbox that also uses a combination lock?

    your idea could have some advantages tho, for instance, I am headed off to college next month and if i had one that only opened with a bolted down key the only place you could open it would be my dorm, and if I'm in my dorm it would be hard to open without my knowledge and anytime i left my dorm i would carry it with me. Even if i lost the cryptex all i would have to do to ensure that it remains locked is make sure no one has access to the key

    well if not that maybe make a key chain charm thats the key esp hand if its not obvious

    Not if you used solar power or a twist nob or just an on off switch it only has to be on when your at the spot you need to be and that would make it hard for the unauthorized personal to get in..

    Solar power would be a bit impractical.  Any cell used to provide the minimum necessary power would be bigger than the codex.  For that matter, a gps unit and electronics would necessitate a massive codex.  It would probably end up almost the size of a summer sausage.

    Your assuming it would be a small box I have seen solar panels about the size of post card that put about 2 AA's worth and There are gps that run on just that, so assuming it is a briefcase for the sake of the argument you have either lets say 2 batts for the gps and 4  for the locking mechanism there you gps lock. We already have time lock briefcases with internal power why not GPS?

    Hey its an idea. At least a start. :)

    check my comment about it already being done the thing is that the box is a large one about 5 feet by 3 feet by 3 feet an has a cell that puts out 9 volts on it

    My sincere apologies, I thought we were talking about a cryptex.  Once you leave the classical  shape and function behind you are really designing a portable safe. 
    If you remove the limits of the cryptex size and shape then the possibilities and problems expand manyfold.  For a briefcase you lose the issue of size but then lose certain characteristics that have their own advantages.  With the cryptex you are trying to store a small and usually singular piece of paper and can play with ideas of tamperproofing it or hiding it.  When the object becomes larger it opens more area for problems. 
    Now the addition of electronics to the equation is very much the next step but one that can destroy the original concept.  As for my own ideas I'd say that the best way to use electronics would be in the form of an electronic key but keeping everything else the same.  A nicely small chip and electronics  could operate a tiny solenoid from power provided by the external key.  That way it would require the knowledge of the few character user password and the many character electronic key without taking overly much room.  The whole thing could be managed by a miniusb plug.

    now there's an idea, would that be a battery powered keypad with with a USB cord? If so you may need some serious encryption software to prevent someone from using a computer to crack it open. Maybe a "no mistake" pass word where it will lock up for a time. THat would be kind of cool