Who among us hasn't slogged away at a puzzle only to find a piece or two missing at the very end? And, worse still, what if you buy a brand new puzzle and it's missing a piece, too?! Friends, it happens. It happened to me just last month.

See, I splurged on a really nice, new puzzle for my sweet pea. We put it together—all the while taking great care not to lose any pieces. Nevertheless, there was one piece missing. We looked everywhere. It was as if that individual piece had never even existed. I was (temporarily) bummed.

I weighed my options. Sure, some people might call the shopkeeper to complain. Some might contact the puzzle manufacturer to inquire about securing a replacement piece. (I am not one of these people.)

Maybe I should just stuff this experience deep down inside the place where I store all of my general regrets and disappointments. Ah, but then I had a better idea!

While I could trace the missing piece and make some sort of replacement out of a spare bit of cardboard, I wanted to make a new piece that would look and feel as close to the real thing as possible. I tried a few different methods and finally found one that worked pretty well.

But before I go into all that process stuff, I wanted to share one or two other thoughts with you. First, the way I see it, this Instructable has the potential to open new gift-giving vistas. Say you come across what would be The Most Perfect Puzzle for So-And-So's Birthday! at a thrift shop or garage sale. The puzzle costs just a buck or two, it looks clean, and it doesn't smell too weird. (Maybe it even features a quaint kitchen scene filled with owls baking a squirrelly soufflé?!) But what if it's missing pieces? Now you can make convincing replacements as needed—and come away with a pretty decent (and inexpensive!) gift.

Oh, you're not a puzzle person? And you don't know any puzzle-y people? That's OK. I think you are still bound to get something useful from this Instructable. Here goes. . .

OTHER THINGS YOU MIGHT GET FROM THIS INSTRUCTABLE

An introduction to a great, free design resource that I love—Canva.com
Air-drying porcelain clay is a very handy thing!
An introduction to TheCrafsMan SteadyCraftin (You're in for such a treat!) and some notes on molding putties.
How to make your own recycled paperboard.
This heads-up: I have one other fix-it Instructable, Fix a Dented Democracy that you might like. (It's a little dated, but still pretty relevant if you live in the United States.)

Step 1: Step 1: Identify Missing Puzzle Piece(s) and Gather Your Supplies.

Have a problem puzzle of your own? First thing you need to do is to put the whole thing together, so you know exactly which piece is missing. You also will need to take one high-quality digital photo of the box your puzzle came in and one more photo of the put-together puzzle (or the puzzle area) which includes the hole where the missing piece would have gone.

You should also gather this stuff:

RAW MATERIALS

air-drying porcelain clay
two-part silicone molding putty (I used an Alumilite Amazing Mold Putty Kit, but you can actually make your own on the cheap.)
glue/Mod Podge matte medium
cardboard
white office paper

MISC. TOOLS

scissors
old blender
large spoon
knife
window screen and bowl (or paper making mould and deckle)
paintbrush
ruler/tape measure
iron or flatiron (optional)

Finally, at least part of the time, you will need access to an Internet-connected computer. (See Step 7.)

Step 2: Create a Replica of the Missing Piece.

I used air-drying porcelain clay to create a replica—or a positive—of my missing piece. I'd originally looked into a lot of different air-drying clay products as well as oven-bake clays before settling on air-drying porcelain clay for this task. I chose it because it seems to be well-suited to picking up very fine detail. It doesn't seem as prone to cracking as other air-drying clays might be either. I steered clear of the oven-bake stuff, because I was concerned that they could stain or damage any surrounding puzzle pieces with which they made contact.

(Note: The video at the top of this Instructable includes the process described in this step as well as Steps 2 through 6 and Step 8. Step 7 has its own video.)

MAKING YOUR MISSING PIECE REPLICA

Work a small amount of porcelain clay in your hands until it becomes warm and pliable. Roll this into a small ball and press it into part of the void where the missing puzzle piece belongs. Repeat this process until you've filled the area with a layer of clay. Make sure that the top of the clay is uniformly smooth and is seated at the same depth as the rest of the puzzle's pieces.
Use the tip of a knife to remove any excess clay from around the edge of the piece. Check the other puzzle pieces for signs of clay, too. Clean these up right away as needed.
Remove the puzzle pieces which surround the clay piece. (Take care not to move or distort it in the process.) Leave the porcelain replica in place until it is hard and dry.
Once it has dried completely, it's safe to handle. If you like, you can even put the puzzle back together and check to see whether your replica plays nicely with the other pieces.

Step 3: Make a Mold of the Replica Piece.

For this step, I used the end of an Alumilite Amazing Mold Putty Kit I had leftover from another project. It's expensive stuff, but it does work well. Still, there are other ways to achieve a similar result. (Check out this DIY putty episode from TheCrafsMan SteadyCraftin to learn more. . .)

Anyway, my molding putty came in two parts. When kneaded thoroughly together, they set up in 15 to 20 minutes, so I had to work relatively quickly.

MAKING THE MOLD

Mix together equal parts of the white and yellow putty from Alumilite Amazing Mold Putty Kit. When mixed well, you should have one malleable, uniformly yellow blob.
Form the putty into a thick, slightly flattened slab. Make sure it is as uniform and smooth as possible.
Center your porcelain clay replica piece onto the putty slab and press it straight down into the material. (Note: You'll have a better result if the front face of your paperboard puzzle piece is as smooth as possible. This, after all, is the side to which you'll be gluing the digital/printed artwork. So, before you press it down into the putty, flip your replica piece over so that the front “face” of the puzzle piece is what you are pushing down into the putty. Meanwhile, the backside of the piece could end up looking just a tiny bit lumpy—not as big a deal if that is the back of the finished puzzle piece.)
The replica should make good contact with the mold, so use the end of a paintbrush (or similar utensil) to lightly press portions of the replica further into the putty. (In part, the thickness of your finished puzzle piece will be determined by the depth of the replica within the putty mold material.)

Once the putty has cured, it will feel hard and rubbery to the touch.

Step 4: Make Paperboard Slurry.

To make a puzzle piece with a similar feel and thickness to the other pieces from your puzzle, you're going to need to make a heavy cardboard/paperboard slurry. This is actually very quick and easy. All you need is a little bit of cardboard—toilet paper tubes, pizza boxes, that kind of thing—and a tiny bit of office paper. (I substituted some brown paper bag which worked just as well.)

MAKING THE SLURRY

Use scissors to cut a little bit of your paper into small pieces. Put these into your blender. (Note: I have a junky-but-reliable old blender that I use just for pulping weird stuff and I have a different blender for processing actual food.)
Use scissors to cut a little of the cardboard into very small pieces and drop these into the blender, too.
Add about five cups of water, secure the blender lid, and begin blending. Try different speeds/settings as needed.
Keep going until the paper/cardboard mixture becomes thick and pulpy. (It should look brownish and cloudy.)

Step 5: Pour Paperboard Slurry Into Mold.

You don't need an official paper making mould and deckle for this project. You can just as easily use a bit of window screen and a large bowl. Place the puzzle piece mold onto the screen and then position the screen over your large bowl to catch the excess water that will drip through during this process.

FORMING YOUR PAPERBOARD PUZZLE PIECE

Using a large spoon, dip out some of the slurry mix and drop it into your puzzle piece mold. The heavy paper fibers will find one another and sink to the bottom while the water will rise to the surface.
Continue to add more spoonfuls of slurry. Take your time and wait for the water to float up.
Gently press your spoon into the mold to help release excess water as you go. (Note: Resist the temptation to turn the mold upside-down to squeeze the water out. This distorts the shape of the piece and can cause it to pop out of the mold and stick to your hand instead. Learned this the hard way myself!)
Once you've piled up as much pulp as will fit in the mold, carefully smooth any high spots with your fingers, so that the material in the mold is level.

Odds are you'll have a lot left over from this batch of paperboard slurry—especially if you are only re-creating a single puzzle piece. The good news? Strain (and wring out) as much of the water as you can and then put the remaining moist pulp in an airtight container. Pop this in the fridge and it should keep indefinitely. The next time you need to make more puzzle pieces, you'll be ready.

Step 6: Test Fit Your Paperboard Puzzle Piece. (Ironing Optional.)

TESTING, TESTING...

Before you pop it out of the mold, allow the paperboard piece to dry considerably. (If you are really careful, you can speed this process with a hair drier or heat gun.) Once the piece is almost dry, you can check the size/shape of the piece by putting it in your puzzle. Just be careful not to damage any of the other nearby pieces as you do this. How well does it fit? This is your last chance to make any tiny adjustments to your paperboard piece as needed.

Optional: If all looks good, you can finish drying and hardening the piece by ironing it. (A flat iron works really well for this!)

Step 7: Use Canva and Color Printing to Digitally Re-Create Missing Puzzle Piece Artwork.

Just as the video at the top of this Instructable shows all of the "analog" steps involved in re-creating a missing puzzle piece, the video at the top of this step shows the digital methods you can follow in order to produce the artwork that will go on the front of your re-created puzzle piece.

Remember, you need to take one high-quality digital photo of the box your puzzle came in and one more photo of the put-together puzzle (or the puzzle area) which includes the hole where the missing piece would have gone.

You will also need access to an Internet-connected computer.

In the video above, I use Canva.com—a free and very robust design website—to match up the box lid with the missing puzzle piece. I end up with a digital file that can be printed on a good color printer or saved on a flash drive or emailed to an outside printshop or office supply store copy center.

Speaking of which, the one thing I would have done differently is to pay closer attention to the color output I got from the printer at my local office supply shop. I could have taken the puzzle box with me or maybe some of the nearby puzzle pieces so that I could make sure that the color matched as closely as possible. Although the color in my digital files looked as if the color matched well, looking back on it, I think the printer probably should have been adjusted.

Step 8: Cut Out Puzzle Piece Artwork, Glue to Paperboard Backing, and Add Matte Finish.

THE LAST STEPS AND FINISHING TOUCHES

Steps 1. and 2. Grab the color copy of your puzzle piece artwork and carefully cut out one of the paper puzzle pieces. If you mess up, you should have extras, so you can try try try again.

3. Use a paintbrush to apply some thinned-out glue (or Mod Podge or a similar product) onto the front of the paperboard puzzle piece. Very carefully place your paper cut-out onto the glue-covered piece, so that the features of both match up perfectly—or as close to perfectly as possible.

4. Add a light topcoat of glue/Mod Podge to seal and protect the puzzle piece. (I like Mod Podge for this, because the texture of its finish can fairly closely match that of other puzzle pieces.)

Finish by painting the back and sides of the puzzle piece with a light coating of glue/Mod Podge and set it aside to dry completely before finally putting it in its rightful place in the puzzle—now complete.

:-)