# How to Make a Cryptex

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In this Instructable I'll show how I made my cryptex.

There is already an Instructable on making a cryptex published lately, but I wasn't satisfied by that one. That cryptex was held together on the outside, like this. I prefer my cryptex held together from the inside, like this. That is by the way the 'real' cryptex, like it is used in the film. Those are harder to make.

A cryptex is a kind of lock with a password, that holds a roll of paper. Author Dan Brown said in his "Da Vinci Code", a book from some years ago, that Leonardo da Vinci invented it, to let messengers carry secret papyrus rolls that the messengers themselves may not read; only the sender and the recipient know the password. If the messenger would smash the cryptex to read the message, a vial containing vinegar which was rolled inside of the papyrus roll would also break even earlier than the cryptex itself, the vinegar would spread over the message, disolve the ink, making it unreadable.
The term 'cryptex' is actually made up by Dan Brown. I don't even know for sure that it's true that Da Vinci invented it, he never actually made one, he would have made a blueprint in his diary, but I never found that page of his diary(so I made my own blueprint, see the next step). What I do know, is that the vinegar thing doesn't work. It doesn't disolve the ink so much that it gets unreadable, it becomes only a little more vague. I tested it with Black Indian ink, several kinds of pen inks, marker pens, ecoline, pencils, and some more; it never worked, just like Wikipedia says.
In the Da Vinci Code, the cryptexes were used different than how they were meant by Da Vinci, in the story they use it as a part of a big puzzle, the answer to a riddle is the password of a cryptex, which contains another riddle that leads to another cryptex, etc. To my opinion the use of cryptexes in such a way is a bit ridiculous, the characters in the book could've just put the cryptex in the freezer so that the vinegar gets frozen, then they could saw it open without danger. But they didn't think of that easy solution in the book.

edit:
In the comments below, 'cavingboy92' came up with this genious way to make use of the vinegar vial: on the paper around the vial, don't write with ink, but also with vinegar. If you want to read the message, pour a PH indicator on it(like red cabbage juice), and you can see the text. Or you can just hold it under a low heat source like a light bulb, then you can see it too, because the acid will oxidate.
If the vial breaks, the piece of paper gets all drenched in vinegar, so it's absolutely sure that it's unreadable!
Here is the proof that it works, tested by cavingboy92.
You could also just put the same inkin the vial as the ink where you wrote with on the paper, that would also destroy the message.
If you want more ways on how you could use a vial-break-delfdestroy mechanism, read throught the comments below, there are a lot of people giving suggestions for it, and also on improving the cryptex.
Finally, if you disolve a lot of salt in the vinegar, I think you can lower the freezing point of it so much that it can't get frozen in a normal kitchen freezer, then the freeze method also won't work so easily, you would have to find a special freezer in a lab or something.

## Step 1: The Blueprint

Here is a blueprint for the cryptex, see the image below. A bigger version is found here. Try to understand it; when you are building this, you should really know what's going on. If you don't understand it, read through all steps before you start to build. I recommend to read through it anyway.

edit:
I got a question about the dimensions I used, these are my measurements:
the whole cryptex
length(from point to point): 14.5 cm / 5.7 in
diameter: 4 cm / 1.6 in

tubes(the diameter is including the thickness)
4th tube(largest): diameter 4 cm / 1.6 in, thickness 0.4 cm / 0.15 in PVC
3th tube: diameter 3.2 cm / 1.25 in, thickness 0,4 cm / 0,15 in PVC
2th tube: diameter 2.5 cm / 1 in, thickness 0.13 cm / 0.05 in ALUMINUM
1th tube: diameter 2.2 cm / 0.85 in, thickness 0.2 cm / 0.07 in STEEL

dials
the dials are made from the 4th tube and the 3th tube, on the outer side, to the 4th tube, they are 1.5 cm / 0.6 in wide, the inner part, made from the 3th tube, is a little smaller, just that a nail fits between.

You don't need to use these dimensions, there are just some requirements for the dimensions of the tubes, see that in the text at the next step.

## Step 2: Materials and Tools

These are the things I used to make the cryptex. If you don't have some things, there may be another way to do it, just look where I used the material or tool, and look if you can think of a surrogate.

The choice of the four tubes is really important. They have to fit in eachother, with not too much space between them, and also not too little(they still need to be able to move in eachother.) The two outer tubes are an exception to this, they may fit real tight. I have the outer tubes as PVC tubes, I think that's the best choice, and the inner two tubes I have in metal. The second smallest tube doesn't need to be in metal, but the smallest is better in metal, I think. That is because we will hammer 6 nails through it, which need to stay in that place. That's why we solder it from the inside, to that the nails stay in place. you could use a PVC tube for the smallest tube, but then it better have a thick frame, for the nails. These nails are so important because they are the tabs that go through the notches on the rings. They may not break.

## Step 3: The Inner Tubes

1: First, if there is rust on your metal tubes, sand it off. They need to be smooth. If there is rust on the inside, like I had, wrap sandpaper around a stave and move it back and forth through the tube. what you can't see on this picture, is that this piece of tube was already sewed off, I took it a little wide because the exact length will be sewed later on.
2: these are the two smallest tubes. The second-but-smallest already has an incision, where nails fit in.
3: Drill holes in the smallest tube, all spaces between them equal, and on a straight line. The space between them will be the length of the rings aswell; 1,5 cm for me.
4: So now the holes and the incision can overlap.
5: Look how long the nails should be. they should go from the smallest rube to the third tube, and not touch the 4th tube. For me that was 0,7cm.
6: Cut them off on the length we just measured.
7: Hold the smallest tube so, that the holes are on bottom. Now get the nails in the holes, from the inside! So the head of the nails should be inside of the tube. This is a nasty job, you can use scissors or something as a help.
8: Lie solderin the bottom of the pipe, so on the nail heads.
9: Now melt the solder. I did it with a flaming solder iron, but it's no problem if you don't have that, because you can also do it in the oven. Perhaps that's even better because the flame made the inside of my tube charcoaly. If you do it in the oven, just place the tube on both sides on something and set the oven above the melting point of solder, I think 200 degrees Celcius will do for most types of solder. Don't forget to brush some sulphur stuff on the nails! The solder should also fill the close the holes with the nails fully.
10: The third tube should also get an incision, make this incision a little wider than the first one, because it will be the inner part of the rings. If this incision is real small, the one trying to open the cryptex needs to align the rings extremely straight, that it might even not open when the correct password is there, because some rings are just a little offset.
11: This is when I cut the nails off, but you probably already did that.

## Step 4: The Rings

1: Now saw rings of the 3rd tube, that fit closely in the space between the nails. Round the edges.
2: Saw rings out of the 4th tube, which cover the smaller rings including the nails. So they should cover all.
3: Glue them together with superglue...
4: ...So that you get this, without the paint. I painted it already, indeed not in the color like you saw it in the introduction, that's because later on I got insatisfied with this colour. I made the inside black, so that, if there would be a little gap between the outer rings, you couldn't see that so easy(no reflection)
5: You have some rings now, paint them. And print alphabet strips, with the length of the outline of the rings; for me was the outline 13.0cm. See the next image if you want to use my alphabet strip.
alphabet strip: I based this on the alhpabet strip from the Da Vinci Code movie, it's almost the same. print in so that it fits exactly around the rings. A bigger image of mine is here.
6: Now line the notches in the rings up, like this. Do it as precise as possible.
7: glue the strip on the rings with hobbyglue, with the letters of your password on one line.
8: Add thin varnish to protect the strips and the rings. I used Varathane varnish which is actually designed for wooden floors, but it is paperfriendly and thin.

edit:
You can also engrave the pvc rings if you like, you can do it with a Dremel, or you can unroll a paperclip, hold it in a burner till it glows, and write letters in the PVC. You need to frequently hold the paperclip in the fire. There are indications that PVC fumes give a higher risk of getting cancer, so do it in a well ventilated area.
This is a lot more work than glueing a strip on it, but it may look better if you do it well.

## Step 5: The Sides

1: Grind one side of the 2nd tube flat.
2: Get two more rings like the other rings, but the inner and outer part need the same width. they don't necessarily need to be the same width as the 'lock' rings. but on of the needs a notch like those rings, and the other not. But it's no problem if that one does have a notch. Mine has, because i made these off the rests of the tubes I used. Glue the parts together, and while still dyring, you can take the one with the notch for the next step.
3: Glue this ring on that tube. Don't worry if it doesn't donnect properly, this is just a temporary solution, later on, we'll connect them with nails. When this and the other ring is drying, we'll do some other things in the next steps.
4: We're going to make these now. Maybe it looks hard to do, but it isn't, I'll learn you a trick with the Dremel.
5: Take some wood that is a bit round and a screw that can be hold by the Dremel.
6: Decapitate the screw. You probably can't do this with your hands, so place the pincer with the screw in the bench vice and start turning it. Wear glasses, the screw will shoot away. It is also better to place something on the screw already, so it's heavier, and will fall down instead of flying away and you losing it.
7: Place it in the Dremel.
8: Put the piece of wood on it in the middle.
9: Hold it on rough sandpaper like this, and let the Dremel do the work for you. You can still move it a bit while it's turning to make the process even faster. Let the Dremel turn so fast that it just not leaves black spots on the wood. WARNING: You really need to wear glasses with this. The Dremel turns fast and shoots off particles from the sandpaper. This could injure your eyes.
10: Pretty smooth.
11: Make the sides a little smooth aswell.
12: Now we have this, sand the bottoms to make them the same height
13: This is the result. Later on, I made these even some flatter, because I found them too high.
14: Take flat wood
15: Measure this radius with a compass(the piece of wood will go over it)
16: Draw two circles with that radius.
17: Saw them out, you only need to do that roughly, because we will repeat the Dremel trick! The place of the screw is easy to find, because the compass left a hole in the middle.
18: The result of Dremeling.
19: Glue them together, a screw will go through them later.
20: I painted it but that wasn't a good idea, so don't do it yet. A lot of paint went off later because I still needed to work with it, so I had to repaint it later. But look at the cylinder with the yellow border, I made that with the Dremel, it fits in the smallest tube. See the next step for why we need it.
21: First drill some holes in the ring we glued on the second tube, and bring nails in them, also with glue.
22: Cut off the nails on both sides after a bit of drying.
23: Sand both sides smooth with the Dremel.
24: Put a screw in the middle through that cylinder, and connect it to the thing on the left.
25: You now have that on the left. Bring the dial rings around the cryptex, and also the inner tube. We need to know it's natural place for the next steps.
26: Put some glue on the beginning of the smallest tube.
27: Put the part we jsut made, in it. Let it dry for a moment and then take the whole inner thing out, by pushing from the other side.
28: Smash nails through it. I first drilled the holes.
29: Cut of the nails and Dremel it smooth. I wrapped fishline around the wooden part, because there was a little crack, and now it can't crack further.
30: We now have this, bring the other ring around the tube.
31: Saw the tube off, Make it so that nails fit in holes through it like the first time, but this time don't cut them off yet!...
32: ...Because they should be smashed through this wooden thing, again a product of the Dremel trick...
33: ...But first connect that thing to that other end.
34: Now the nails are smashed in, and Dremeled smooth.

## Step 6: Finishing

Paint and varnish the sides, and you're finished! Also add some traingles, arrows, or something else on the sides to show where the password should be.

Now you can make a riddle that looks old. Stir some coffee powder in water(You can also do it with normal coffee but I think this works even better), and drench a poem/riddle in it. Take a candle and gently burn the edges. scratch off some grey ashy stuff from the edges and your riddle looks old.

Here is an example of a riddle you could use:
He who makes it, sells it.
He who buys it, doesn't use it.
He who uses it, will never know...
see the answer here

I tried to make my riddle a little Da Vinci Code-like, but my rhyming in English is bad I think. The answer to my riddle is 'oyster'.

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## 366 Discussions

FYI it's India ink, not "Indian".

Hi! This was almost 10 years ago and I don't exactly remember how I did that. I probably fixed the tube and fixed two pieces of wood above it to make a straight gap for a metal saw... Or i just used a Dremel metal cutter blade and did it straight by hand.

I just came across this today but does anyone have a US version of this? I kinda get the jist of how this works, kinda. I'd like to make a small cheap one out of thick cardboard tubes first and then make them from better materials.

I have made one from plans from popular woodworking magazine. They were indepth instructions. I think it was from 2007 or so

Just a few questions:
1. What kind of vial do you recommend?
2. Where can I get that vial?
3. What part of the cryptex breaks the vial when forced open?

In the movie it said the vinegar dissolves the papayrus, not the ink

I just realized, you can make the container part as long as you want, the pins only have to be in the key wheel section. Off to search for longer pipes.

Interesting...
But, really with trial and error, you could crack the code...

But, i still want one

5 replies

trial and error won't work. This one has over 308,915,776 combinations and only one is correct. There are 26 letters on all 6 dials. It's highly unlikely that trial and error would ever work

Actually you can crack it with trial and error. All you have to do is crack one letter at a time starting from the opposite end that the dial pulls out of and EVENTUALLY you will get it. And if you use actual words like OP did, all you have to do is be good at word puzzles because if you know a few of the final letters you can guess the whole word.

Oh wait, i didnt think of what istarian said...

Trial and error will work just fine, you'll be there a long time though. The biggest dilemma is that a well-built cryptex will require you to discover each digit in the combination before you can test if it's right because no movement is possible until all the pegs are free to move...

If you tried one combination a second for 16 waking hours, with all the possibilities available on this cryptex, it would take you a little over 14.5 years to try them all. So I refute your claim to "trial and error [working] just fine" unless you've really got nothing better to do.

how about a vial of ink? self explanatory, and it will make a mess, so you will know if someone tried to break it