I don’t update this site much anymore due to my writing work elsewhere, but I do answer emails that come in. They’re normally about one of two things: my geocaching cryptex, or my Leatherman PS4 mods. To save myself from having to explain how to make a cryptex to everyone, here’s a quick rundown on how to do it.

Making a cryptex is all about understanding the mechanics. Once you do, you’ll be able to adapt the mechanism however you want. To better explain how it works, I drew up a quick 3D model of a basic cryptex withonly one lock wheel attached in Google Sketchup

The basic parts in a cryptex are an inner tube, an outer tube, and lock wheels. The inner tube is here red. The blue knob on the picture is attached to the inner tube and acts as a pin in a lock. On a complete cryptex, you’ll have one for each lock wheel. The outer tube, here yellow, should be just big enough to house the inner tube. It also needs a cut down the length of it so that the lock pins/knobs/whateveryouwanttocallthem on the inner tube can fit through the outer tube, making it possible for the inner tube to be inserted into the outer tube with the knobs sliding down the outer tube cut/track/opening/whatever.

The inner tube is what holds you “treasure”. The point of a cryptex is to make the inner tube removable only when the correct combination is entered with the lock wheels. To stop the inner tube from being removed, you have to create a barrier so that the knobs that stick out of the inner tube and through the outer tube gets stuck on something. That’s where the lock wheels come in. Their inner hole should initially be made to fit the outer tube exactly, so that the lock wheels can spin around it. The lck wheels need to be at least twice as thick as the knobs. You then need to duplicate the mechanism seen in the second picture above – half the thickness of the lock wheel should be a wider hole to let the knob spin freely, and the other half should only have a small portion of it cut out to let the knob through.

When the inner tube is inserted completely, the lock wheels will be able to spin freely because the knobs are located in the half of the lock wheel that has a cutout all the way around, like the position in the second image above. However, to remove the inner tube, all the tiny cutouts in the other half of the lock wheel also have to line up to create a single uninterrupted track for the knobs to slide through as the  inner tube is removed. Naturally, the right combination will be the one that makes all these cutouts line up, whereas any wrong combination will have at least one misaligned cutout to prevent the knobs to slide out.

This is how you make a “proper” cryptex, but it can be done simple. My cryptex doesn’t have one knob for each wheel, and it doesn’t have the two different cutouts for each lock wheel. Instead, it has only two knobs. When the inner tube is fully inserted, these knobs rest inside the 6th wheel and end cap of the cryptex, respectively. This allows the other 6 wheels – that is, number 1-5 and 7 – to move freely, even though they only have a cutout that lines up in a certain position. This is easier to make, but easier to “cheat” to open. In theory, you can open a cryptex by pulling on the inner tube while turning all wheels at different speeds. Due to the different speeds, all wheels will sooner or later line up – but it can take ages. Fewer pins/knobs like in my crpytex means you only need to line up two wheels at a time. However, my cryptex is a geocache, so if people really want to cheat that badly, go ahead.

Hopefully this made a light turn on for anyone reading it and wondering how a cryptex works. If not, well, I can’t help you. This might, however.