DIY - Cryptex

I recently watched Ron Howard's 2006 film The Da Vinci Code. If I had to remember just one thing from the film, it would surely be a single object: the cryptex. A kind of cylindrical padlock with letters that can hold any small object. I was deeply interested in this object, as I found it incredible to be able to seal a letter, a USB key or even a bit of money with just a word. So I found out more about the mechanism, so that I could recreate one myself at a lower cost.

• Computer
• 3D printer with PLA or ABS filament
• Glue

After several hours of research, I began the modeling phase, choosing to create a fairly small model (only 9 cm long). By preference, I chose to put only 6 washers of 26 letters each, which makes 26^6 possibilities, or just over 300 million. So, if someone were to try to make all the possibilities, considering that they would only have 12 hours a day and that they test a possibility every 2 seconds, it would take them over 36 years!

I've chosen to create the most minimalist model possible. But it is possible to customize the templates I've provided as you wish. To do so, I recommend using the STEP files. For example, I created this cryptex for Mother's Day. You can also add a loop so that it can be attached to your key ring.

When creating mechanisms like this, the hardest thing to manage is surely the margin left. To check that everything fit together perfectly, I created a virtual assembly on my modeling software (OnShape) and created a plan. Once this verification stage had been completed, it was time to run our model through the cutting software.

First, it's a good idea to choose your password, so that you can print only the letters you need. Then insert your files into your cutting software: 

• Ring × 7
• P1 × 1
• P2 × 1
• Your 6 chosen letters

Personally, I use the Ultimaker Cura cutting software, because it's free, complete and very intuitive. I keep the basic settings for PLA with standard quality, with a few exceptions: 

• I choose a 10% gyroid fill
• I choose tree-type supports

If you wish, you can change the scale at which you print your cryptex, but there's no guarantee that the margins will still be correct.

The best thing about this model is its ease of assembly. A word of clarification before we finish: if you feel like painting it, it's probably best to do so before assembly. To assemble, you need to insert the rings and letters alternately, starting with the last letter of your password. There's almost nothing to glue, except the last ring (see image), so that when you use your cryptex, the letters stay securely in place.

Now all you have to do is use it to hide any small object: a secret message, jewels, keys, money, and so on. To enter the code, simply line up the right letters at the 2 arrows. I hope you enjoyed this Instructables and thank you for taking the time to read it. If you've printed and customized it, please feel free to share it with me. As for me, my printer is being serviced at the moment, I had already printed a first version offered to someone and I wanted to reprint one for this Instructables, to better illustrate my explanations, but unfortunately I wasn't able to do it in time.