DIY PVC Cryptex (Metric)




Introduction: DIY PVC Cryptex (Metric)

About: Partner, Dad (of 5), home handyman, toy fixer-upper, battery finder, phone fixer, dog walker, bike rider, Band-Aid applier, toilet taker, golfer, breakfast maker, dishwasher stacker, trinket project creator.

Welcome to my 'at home' DIY PVC Cryptex build. What you are about to read (or watch) is my own take on the popular design seen out there by Soxter (only this one will be in METRIC dimensions utilising materials from my local hardware store here in Australia).


Ben (auzzy_mate)

Step 1: Advantages

Now you may have seen a few of these around, but from all accounts this will be the only one out there that is published in public dimensions. I have spent a bit of time planning this one out on paper after visiting my local hardware store and what I have come up with is a design that has two main benefits:

  • there is minimal sanding, and
  • it has a bigger space inside for hidden items (42mm as opposed to 19mm of other imperial designs).

Step 2: Materials

It may be harder to by short lengths of the PVC / DWV pipe, but buying it in 1meter lengths will just allow you to make more. You could also get lucky and fins some lying around any building site/house renovation.

All in all to purchase the bits required it works out to about $10.40 at 2016 prices to make one of these cryptex's.

Step 3: A3 Schematic

If you print this page out in A3 size you can glue it together to see how the build should go.

Step 4: Combination Rings

In this step you will build the Combination Rings (CR) which are used to lock the Cryptex closed:

  1. Gather the 50mm PVC pipe and 65mm DWV pipe (glue, saw, sandpaper, clamps),
  2. Cut the 65mm DWV pipe into 4x25mm & 1x3mm pieces to make the Outer Rings (OR),
  3. Cut the 50mm PVC pipe into 3x15mm, 1x10mm & 1x3mm pieces to make the InnerRings (IR),
  4. Cut a 2mm 'slot' across the IR's (sand to smooth the cut)
  5. Glue the IR into the OR to make the CombinationRings and KeeperRing (KR is 3mm) making sure one edge of the IR aligns with the OR, (use the clamps to hole the pieces together while the glue dries),
  6. Fit the glues CR/KR onto the 50mm DWV pipe to see how they fit together (adjust their order to find the best fit (the CR with the 10mm IR has to be on the left and the 3mm KR has to be on the right), and
  7. Mark the rings "1 / 2 / 3 / 4" so as to remember what order they sit in, also mark the position on the CR where the slot is.

Step 5: Female End

In this step you will build the female end of the Cryptex (which will hold the CR's and KR):

  1. Gather 1x60mm PVC End Cap, 1x50mm DWV Coupling and 50mm DWV pipe (glue, saw, sandpaper, KR),
  2. Sand one end of the DWV Coupling to fit inside the PVC End Cap (should only take 3-4mins),
  3. Cut the DWV Coupler in half (30mm),
  4. Fit the DWV Pipe all the way into the Coupler piece, then fit that inside the End Cap (leaving the Coupler piece with a 3-4mm overhang out of the End Cap),
  5. Mark a ring around the edge where the Coupler sits,
  6. Mark the (lengthways) slot that is to be cut for the screws/bolts,
  7. Mark and cut the DWV Pipe at 100mm from the Coupler line (drawn in step 5),
  8. Cut the slot, and
  9. Glue the KR to the end of DWV Pipe (to the end with the open slot)(use clips from making the CR's).

Step 6: Male End

In this step you will build the male end (which will hold the locking pins/screws/bolts AND the hidden items):

  1. Gather the 1x PVC End Cap, 1x PVC Coupling and 40mm PVC Pipe (saw, screws, glue),
  2. Cut the larger end of the Coupling (end with small internal groove) so it is 30mm in size,
  3. Fit the Coupling inside the End Cap (it should go easily inside (no forcing),
  4. Fit the 40mm pipe inside the Coupler and mark the pipe all the way round,
  5. Remove the Coupler and End cap,
  6. Mark a line all the way round 3mm from the Coupler Line to indicate where the KR will sit,
  7. Mark and cut the PVC pipe 143mm from the Coupler line (140mm + 3mm for the KR),
  8. Draw a straight line (lengthways) down the pipe and mark drill holes at 20mm / 45mm / 70mm / 90mm from the KR line,
  9. Re-place the PVC pipe into PVC Coupler and then into the PVC End Cap, then place the Female End over the male end and check the position of the drill holes in relation to the CR's,
  10. Drill hole number 4, insert the screw/bolt, then put back together with CR#4 on the female end and check the fit (make sure the CR spins without rubbing), and
  11. Continue with CR #3, #2 and finally #1: testing the spin each time.

Step 7: Glue

In this step you will be doing the final gluing:


  1. Glue the Coupler into the End Cap (dont forget the 3-4mm overhang),
  2. Place the CR's onto the DWV Pipe (in the correct order),
  3. Glue the DWV Pipe (with CR's) into the Coupler (push all the way in to the line drawn previously), and
  4. Let dry.


  1. Glue the Coupler into the End Cap (make sure they are flush with each other),
  2. Glue the PVC Pipe into the Coupler (up to the coupler line marked previously), and
  3. Let dry (if you are careful then you can test the male/female ends together: spin all four CR's).

Step 8: Final

Now that your cryptex is all finished and dry, it is ready for labelling / painting or whatever you want to do with it (hopefully you still have the rings marked if it is locked closed).

In my case I used a label maker to make the combination lettering (the circumference of the CR's is 213mm so I used 5mm lettering with 3mm gap to make the 26 letters). Some may choose numbers or colours or images or hieroglyphics (builder preference).

As for colouring, it is possible to clear-coat seal and/or paint the PVC and DWV pipe, but it can be tricky and is covered by other videos online (basically you need to sand/scrub it first and then paint).

Anyway, I hope this has been useful to you but if you have any questions at all then please message me and I will get back to you asap.



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    3 years ago

    Fun puzzle build! :)