I made this with a Trotec speedy 100 for a school project, it's cut from 3 .115" thick wood sheets, and I got the idea from Da3da1u5. I beefed up their ratchet mechanism, scaled the entire thing up to around 4", and made the letter pieces .23 x .23 instead of .115 x .23. So, if you want a puzzle that's a bit more hefty and long-lasting, this is the one for you.

Supplies

3 wood sheets (.115" thick)
Wood glue
Something to paint glue on with, maybe a spare brush or a chunk of leftover wood from a cut
Sandpaper and/or file, whatever's easiest for you

Step 1: Cutting

AutoCAD files are linked, be sure to have the letters and 47 logo burnt on instead of cut.

cryptexparts.dwg
Download

Step 2: Ring Assembly

I messed this part up pretty badly when I started, I glued the ratchet mechanisms the wrong way around on every single disc, and I ended up using another 2 sheets to recut them. Al Gore is probably crying somewhere, but it's no biggie, since you can learn from my screwup. The pictures should help.

*P.S the square cuts in the rings are for aligning them while the glue is drying, there's a .115" rod on the .dwg that you can use. If you really want to be sure, you can even wedge the thin edge of a piece of wood into the keyslot

Step 3: Chamber Assembly

Nice and easy, the only thing you might have to do is sand down the key a little, so it fits into the slots a bit better. You might not even need to use glue (other than on the chamber lid), the holes are all super snug. It's your choice though, I definitely would if you want to be completely sure it won't disintegrate when you try to pull it out. Also, you might have to file/sand down some of the "ribs" if they create too much friction.

*P.S. Make sure the key is aligned with the little notch on the end cap before gluing

Step 4: Gluing the Letters

Definitely the most painful part of this build, make sure you pick your code before gluing the letters. The ones you pick should be aligned with the keyslot. If you plan on gluing the letters in after you've done step 5, make sure to rotate it every now and then to stop it from seeping into the space between discs and drying.

Step 5: Putting Everything Together

All that's left to do is glue the four brackets to the inner pegs. Feel free to sand down anything that fits too snug. The little red marks on the assembly are where the brackets should slot in.

Step 6: Problems With the Final Product

Because there was so much space between the ends of the ratchet arms and the teeth they move on, the active discs have quite a lot of play. This isn't a massive problem, and it still works fine, but you do have to make sure all the discs are perfectly lined up before you pull the chamber out. Making the keyslot a bit bigger, or even sanding it down a bit probably would've fixed this.

Step 7: Conclusion

If I started this all over again, I would make it a bit smaller. 4+ inches is a bit extreme, and something like 3 or even 3.5 would've saved plenty of wood. If I had given myself the time to innovate a little, I would've also made the letter discs a tiny bit bigger than the static ones, just so they'd be easier to grab at. The same goes for the top of the chamber, some kind of D-shaped handle to help yank it out would've been great, and that handle would be a much better indicator of which end the chamber opened on than a tiny gap.