Puzzle Locked Paper Box

I am preparing some escape room mailers for the library, and the limitations of keeping my puzzles less than 1/4" thick and less than an ounce all together so that I can mail them with a single stamp means I needed to get creative! This project is a combination of two fairly simple things: a pop-up origami box, and a simple string and bead puzzle. The puzzle is used to "lock" the box, so that it can't be opened without solving the puzzle, or knowing the solution already.

It's certainly not Fort Knox, but it can be a fun way to make a container for something like a gift card or, as I'm using it, a way to hide a clue as part of a larger game.

As a bonus, since it's so simple, it's easy to make. Let's get started!

• 1 square piece of paper
• a piece of tape for reinforcement
• a length of string or cord
• a hole punch
• two beads, slightly larger than the hole made by the punch
• an exacto or utility knife
• double-sided tape
• optional: reinforcement labels for the hole

First, we need to fold our box. I'm using a precut piece of origami paper that's 6 by 6 inches. You will likely want to use a piece this large or larger, as going smaller than this makes the process of putting together the string puzzle much more troublesome.

First, we need to fold the paper in half diagonally both ways. By this, I mean fold one corner of the paper to the corner directly across from it. If you have a color you'd prefer to be out the outside, make sure you start with that side facing down. Unfold and then repeat with the other corner. When you unfold it the second time, you should have 4 equal triangles created on your paper by the creases.

Next, we'll need the fold the paper in half by folding it edge to edge - that is to say, take the edge of one side and fold it even to the side across from it. Again, we will do this one way, unfold it, and then do the same to the other pair of parallel sides. Now when you unfold it, your creases should make 8 equal triangles.

Now that we have our guiding creases in place, it's time to do our more permanent folds.

Now that we have out guiding creases in place, it's time to start folding our sides!

To start, fold two opposite corners to the center, then, for the last time, unfold.

Take those same corners, and fold them up to the crease line made by the fold in the last step. Then, fold along that crease towards the center.You should have a pair of of trapezoid shaped flaps.

Next, fold those sides to the center line. Your paper should now look like the final picture of these directions. Now it's time for the tricky fold...

If you aren't familiar with origami folds, this may take you a couple tries, and that's ok! I would very much recommend looking closely at the photos instead of just going by my written explanation - it's a bit hard to explain textually.

For ease of following along, orient your paper so the pointed sides are pointing up and down in relation to you.

Find the center line going across your folds - that is, the center line that goes from left to right. Start to fold the top, pointed side down towards that center line. Tuck you finger into the left flap, and, following the folds already creased, fold that flap down to the center line, creating a triangle, as seen in the picture. Repeat on the other side, then fold the entire side down flat.

You'll have a flap with the point facing you, with 4 sides. Two triangles worth of paper will be sticking over the edges - fold those in towards the center line going up and down. Now, fold the pointy flap back towards the side it originated, making the fold along the top of the rectangle above it, made by the folds you just completed.

Rotate the paper 180 degrees, and repeat the process on the other side.

Gently tug the flaps outwards to pop up your origami box. Chose one side,and fold the point down so it looks like an envelope. I also went it and used double-sided tape on the bottom, folded portions of the sides to keep them from popping up and deforming the box while manipulating the puzzle.

Now that our box is folded, it's time to prep the puzzle.

For this step, we'll need a hole punch, a piece of tape, a ruler, and an exacto or utility knife.

Punch a hole on flat flap, using the center crease as a guide.

Take a piece of take and tape is down the center line of the pointy flap. This is there to reinforce the slots/strip we'll be cutting in a moment. I would suggest using painter's or masking tape as they are a bit thicker than scotch tape, which will provide a bit more reinforcement. You could also use electrical tape, but you'll need to be extra sure your blade is sharp, as we'll be cutting through it and it if prone to snag if your knife is a little too dull.You could also use washi tape if you're less interested in reinforcement and just want to give it a bit of pizazz - up to you! You can also reinforce the hole punch with the reinforcement stickers made for that purpose, if you like. I did not do so for this example, but there is a photo of such an item on the materials listing step.

Now we're going to need to measure the diameter of our punched hole. Mine is about 6 mm. We will need to make the strip we are about to cut just a touch smaller than the hole - I'll do 5 mm. Again using that center fold line, which should run down the center, more or less, of your tape, mark your cut lines. I put the 3mm mark on my line and marked at 0 and 5. You'll want to do this twice to mark the start and stop of both your lines - in my case, about 4 cm apart.

Now, just use your ruler and your guidelines to cut two slits in your pointy flap. Don't go all the way to the edge of the paper!

Now it's time to lock it! If you have something you want to put inside, now's the time to do it. First, we're going to need a length of string or cord. I would suggest not going with something TOO thin, as it can bite into the paper and cause tearing. I am using a bit of soft cord ribbon. You'll need to cut a length long enough that it can be threaded through the hole, through the slit, back through the slit, with beads tied on each end. You will almost certainly need a longer piece than you think due to the knots. You'll need 2 beads, and they'll each need to be bigger that the hole you've punched, but only just. If they are too big, the solution will be more difficult, if not impossible.

To assemble: Tie a bead to one end of your cord. Take the cord and string it through your punched hole. Loop it back through the slit on the same side as your bead, then back towards you through the other slit, and then finally back through your punched hole. Tie the other bead to the other end, adjusting so that the length of cord has enough give to be manipulated without allowing the box to fully open. Clip off any excess, and you're done.

You'll see on my example here I tied one of the beads so that it could slide freely, and one was tied firmly in place. I was just experimenting - I would suggest tying it so both can slide freely. This is your red herring for the solution - you don't solve it by fiddling with the beads, but that's where most people start.

The way we assembled our box, you might not realize the solution to the puzzle, though you'd be at an advantage in figuring it out! However, if you need some help figuring it out, or need a refresher, I have a quick video above showing the solution.

For those who need or prefer a textual description of the solution:

To unlock the puzzle box, hold both end of the string in your hands. Gently tug them towards you, while holding the squared flap still. This will pull the strip cut through the opposite, pointed flap through the small hole, making a loop. Release one of the sides of your string, and gently pull the string and bead through the loop of the strip that is protruding through the hole. The string and beads will be completely removed from the box.

If you want to reset the puzzle, just reverse this process!