Piggy Pips

The manual

1 · What this is

Piggy Pips is a set of 1,024 two-sided tablets ("pips"). Each face carries a unique 3–4 letter string; two faces per tablet gives 2,048 strings, which is exactly the BIP-39 English wordlist. Four letters is enough because every BIP-39 word is uniquely identified by its first four characters.

A BIP-39 word encodes exactly 11 bits, so one draw equals one word, with nothing left over and no bias. The core teaching point: the jar isn't a gimmick that approximates a random number generator. It is one, and one whose fairness a child can verify just by looking at it, unlike a chip you can't inspect.

2 · Print your own set

Sets aren't sold anywhere yet, but a set is easy to make. There are two ways, depending on the tools you have.

Option 1: paper and scissors

No 3D printer needed. Print the wordlist on ordinary paper, cut it into slips, and the bowl works exactly the same way:

Download the printable wordlist (PDF) (8 pages, all 2,048 words in a cutting grid)

• Cut along the grid lines into 2,048 slips. Keep them the same size: identical look and feel is what keeps the draw fair. A paper guillotine makes far lighter work of it than scissors.
• Fold each slip once, word inside. Unlike a tablet, a flat slip shows its word, so the fold is what lets you draw without looking. Thicker paper stops the ink showing through.
• Each slip is a straight 1-of-2,048 pick: the same 11 bits per draw as a tablet, with no face to toss. Unfold, write the word down, refold, and return it to the bowl.

Option 2: 3D print the tablets

Download the ready-sliced project file and print all 1,024 two-sided tablets yourself:

Download piggy-pips-2048-words.3mf (35 MB, 4 build plates, 1,024 tablets)

• Material: PLA. It's stiff, cheap, easy to print, and these small flat parts won't warp. A matte finish makes the lettering easier to read.
• Nozzle: 0.4 mm. The 3–4 letter strings are small; a wider nozzle will smudge them. Don't scale the model, the lettering is sized for this nozzle.
• The file is pre-configured: 0.16 mm layers, 2 walls, 15% infill, no supports needed.
• Two colours, no multi-material printer required. Each 3 mm tablet is a light body with a thin dark core, and the engraved lettering cuts into that core so the letters read dark on both faces. The colour swaps sit at fixed heights (0.68 mm and 2.6 mm), so an AMS or dual extruder handles it automatically, and a single-extruder printer manages fine with a filament-change pause at those two layers. Any two contrasting colours work.
• Print all four plates. A partial set is unusable for real generation: with tablets missing, some words can never be drawn. Keep the plates together until the whole set is done.

Whichever way you make it, run the verification in the next section before the set generates anything.

Piggy Pips is built on the Entropia concept by the SeedSigner project.

3 · Before first use: verify the set

Do this once, for every set, before any seed is generated from it. A printing error that duplicates a word, drops one, or misprints a letter silently weakens every seed drawn afterwards, and nothing about the draw will look wrong.

1. Lay the tablets out in alphabetised order.
2. Open the official wordlist: github.com/bitcoin/bips/blob/master/bip-0039/english.txt
3. Check all 2,048 strings are present and none appears twice.
4. Confirm every string is legible on both faces.

If a set fails, retire it as a display or demo-only jar and mark it clearly. Don't repair it by hand-printing the missing tablet. At a workshop, the verification is part of the lesson, not an inconvenience before it.

4 · Generating a seed

You'll need: a verified full set · an opaque bowl deep enough that the contents can't be seen · a signing device such as a SeedSigner, with a calculate-final-word function · pencil and paper.

1. Confirm all 1,024 tablets are in the bowl. Shake thoroughly.
2. Draw without looking. Let the toss decide the face.
3. Write down the word, then return the pip to the bowl and shake again.
4. Repeat until you have 11 words (12-word seed) or 23 words (24-word seed).
5. Enter them into the signing device and let it calculate the final word.

The single most important rule: never choose which face to read. If you pick the side you prefer, you've thrown away one of the eleven bits and replaced it with your own preference, which isn't random. Let gravity decide, every time. This matters most with children, because they'll try to pick the funny word. Frame it as the rule of the game: you don't get to choose. That's the whole point.

5 · About the final word

You draw 11 words, not 12: the twelfth is calculated, because part of it is a checksum built from the first eleven. The honest detail: in a 12-word seed the final word carries 7 entropy bits plus the checksum, and when calculated from 11 drawn words those 7 bits typically default to zero, so the seed holds 121 bits rather than the nominal 128 (24-word: 253 vs 256). Is that a problem? No: 121 bits is far beyond any brute force that will ever exist. But state it honestly rather than claiming 128; overstating security is a bad habit to teach. If your device can supply the remaining bits by coin flip, use it. Returning each pip before the next draw keeps every draw a clean, independent 11 bits, and repeating a word is fine; repeats are legitimate in a seed.

This step is not optional, and it is the one place a device is unavoidable. The checksum is the leading bits of a SHA-256 hash taken over the whole entropy at once, so it can't be looked up word by word or worked out with pencil and paper: only 128 of the 2,048 words are a valid twelfth word for any given eleven (8 of 2,048 for a twenty-fourth). An airgapped signer is the tool for it, and the safety rules above still hold: no radios, nothing that has been online.

The seed this produces is real and it works, which is exactly why it must never hold savings. A functional seed is the point of the exercise: children see a working key come out of a bowl of tablets. But it was made in company, in a room with other people watching, so it was never private and can never be made private afterwards. Fund nothing with it, ever.

6 · Workshop rules

Every seed generated in a room with other people is a demo seed. Always. Say this before the first draw, not after. Children will want to keep their words, and that instinct is correct and worth praising; it's exactly the right feeling about a real seed. Redirect it: "this one is for practice so we can all see how it works. When you make a real one, you'll do it alone, and nobody else will ever see it. That's the difference."

• One shared jar scales better than per-child kits. Give every child at least one draw.
• Count the tablets back in.
• Hand a child the printed BIP-39 list and let them check a drawn word themselves: a small act of verification, the same instinct as running your own node.

7 · What never to do

• Never store entropy. Don't keep a jar in a used arrangement, photograph drawn tablets, or preserve draw order. Write the words, return every tablet.
• Never generate a real seed on camera, on a livestream, or in a room with a phone recording.
• Never reuse a demo seed for real funds, no matter how small.
• Never let anyone choose their own words. That's the same failure as a brain wallet.
• Never top up a set from a second incomplete set.
• Never type drawn words into a connected device.

8 · Care and storage

Store the jar somewhere its presence is unremarkable. The tablets reveal nothing about any seed drawn from them, but to someone who recognises it, a jar is a sign that seeds are generated in this house. Keep the set complete; re-verify all 2,048 after any event where tablets may have gone missing, and at least once a year for a set in regular use.

9 · Attribution

Piggy Pips is built on the Entropia seed-tablet concept created by the SeedSigner project, with our thanks for the open-source work this is built on.