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Toy Workshop of the Future · Book I

Runes

The Book of Spells

Make up a spell, print it as a rune and give it to your sister. It works for her too.

6–12 years · Ø 30 mm rune for kids 6+, Ø 35 mm version for younger ones
Socket Ø 32 mmRC-522 (NFC) reader underneath Thermal printer in the spinespell card, CSN-A2 Wand 280 mmPETG tip = LED diffuser Inside: ESP32-S3,microphone, speaker Rune Ø 30 × 5 mm, NTAG215 sealed in mid-print MMU print:leather brown + gold
Chapter one

The wow moment

My 6-year-old daughter hands her big brother a small green stone with a spiral carved into it: “This is my spell. It’s called Fireflius.” He sets it on his own Book, circles his wand twice, and his room lights up in her blue while her wind chimes ring out. “My spell works on your Book too!”

Chapter two

How it plays

  1. The child tells the Book what the spell should do. The Book is a stand shaped like an open book, with two rune sockets, a microphone and a printer.
  2. Claude turns the wish into a rule in a tiny language with a whitelist (trigger → action). Code validates it and the Book reads it back out loud.
  3. The child performs the wand gesture three times and the code stores its pattern.
  4. The Book prints a spell card, and overnight the 3D printer makes a rune: a 30 mm token with the symbol in MMU colors and an NTAG215 chip sealed inside. The rule itself is written to the chip (JSON up to 504 B), not just an ID.
  5. A rune placed in the Book’s socket “charges” the wand. The wand holds three spells at a time.
  6. Combining: one rune in each socket. Code checks that they fit together (same trigger type, no conflicting actions, at most 4 actions) and Claude comes up with a name for the new spell. The combination gets printed as a new rune.
  7. Spell duel: sibling against sibling, three runes each. Code gives every spell an element and a power level out of a fixed budget, so no spell is “the strongest”. The room lights show how the duel is going.

What it sounds like at the Book

Little sister
“I want it so when I wave my wand up and down, the lamp twinkles like a little star and plays that song with the raindrops.”
The Book
“Got it. When you wave up and down, the lamp in your room blinks white three times and Raindrops plays. Would you like to give this spell a name?”
Little sister
“Stardrop!”
The Book
“Stardrop is written down. Your rune will be ready tomorrow morning. Now show me the wave three times.”
Combining Stardrop + Fireflius
The Book
“These two spells go together: both are cast with the wand. The new spell blinks blue and white and plays both tunes, one after the other. I’m calling it Starry Firefly. Shall I print it?”
An incompatible pair
The Book
“One spell turns the light on and the other turns it off. Together they would just argue. Try a different pair.”
Chapter three · try it

The Rune Altar

Drag two runes into the sockets (or just tap them). Each rune carries the whole rule on its chip. Code checks whether the two fit together, and if they do, a card for the new spell prints out.

Runes on the tray
Checked in code (no LLM)
  • Same trigger type
  • No conflicting actions
  • At most 4 actions

Put a rune in each socket.

Chip contents (JSON rules)
// left socket: empty
// right socket: empty
Card from the thermal printer
The new spell’s card slides out here.

The wand recognizes gestures by itself (MPU6050 accelerometer), no network needed. When a spell is recorded, the child performs the gesture three times and the code stores the pattern. The wand holds three spells at a time.

Chapter four

Why a tenth time, and what only AI can do

Why a tenth time

Runes get collected, given away and swapped like trading cards, except the kids invented them. Combinations open up a whole tree of new spells. The duel gives siblings a contest, and the collection on the shelf is there for everyone to see. The spells keep working (the spell book is permanent), so the toy doesn’t fade like a one-off wow.

What AI makes new

A six-year-old says a rule in plain words, and a minute later it is safe, runnable code. Without an LLM this would take menus or block programming.

The step up from the Rule Box, an earlier round-1 idea, is that the program is a physical object that carries its own code: you can give it away, combine it, and it works without a network.

Chapter five

How it’s built

The altar-book

~220 × 160 × 60 mm, shaped like an open book, two Ø 32 mm sockets for runes, printer slot in the “spine”. MMU: leather brown + gold ornaments.

The wand

280 mm, hollow, spiral (two-color MMU), translucent PETG tip as an LED diffuser, handle with a battery compartment closed by an M2 screw.

The runes

Ø 30 × 5 mm, raised symbol in a contrasting color (MMU), NTAG215 dropped in during a print pause under 1.5 mm of plastic. Ø 30 mm is just under the EN 71-1 small-parts cylinder (31.7 mm), so they are for kids 6+ and not for siblings under 3; there is a Ø 35 mm version for younger ones.

Electronics: bill of materials

PartWhat forPrice (CZK)Source
ESP32-S3 DEVKit (LaskaKit)the Book’s brain448electronics list, sec. 4
RC-522 ×2reading and writing runes in both sockets98#30
NTAG215 (10 pcs)runes~120 estimate#31 NTAG213 only has 144 B
INMP441push-to-talk microphone98#27
MAX98357 + 40 mm speakerthe Book’s voice187#48, #50
CSN-A2 thermal printerspell cards928#67
ESP32-C3 SuperMinithe wand’s brain~100 estimate—
GY-521 (MPU6050)wand gestures79#10
Vibration motorthe spell’s “click”49#61
Li-Po 400 mAh + TP4056wand battery~120 + 20 estimate—
WS2812 (1 pc)glowing tip~10 estimate—
Total~2,260 CZK (about €90)

Architecture: where code ends and the model begins

Child speaks→Book (ESP32)→Gateway: whisper→Claude: rule as JSON schema + name
↳code: whitelist validation + read-back sentence→Book writes the rule to NTAG215
the LLM stops here
Rune in socket→Book reads the JSON→ BLE →wand stores 3 spells
Wand gesture (recognized locally)→wand: LED, vibration, sound|Home Assistant: room lights
■ model■ code, runs offline

The boundary: the model only translates a sentence into JSON and invents names. Validation, spell power, whether a combination fits, duels and casting all run in code, with no LLM at runtime. Actions come in two tiers: wand actions (work anywhere) and room actions (only at home, limited to a whitelist of the kids’ room devices in Home Assistant).

Chapter six

Safety, roadmap and scores

Safety and offline

Saved spells run offline forever, and the rune carries its own code, so it works at a friend’s house too, as long as the friend has a wand. Whitelist: no locks, no heating, no other rooms. Parental time lock (after 8 pm, quiet spells only). Print bigger runes for younger siblings.

Roadmap

  • First playable prototype (a weekend): the Book + one reader, wand-only rules, no printed runes (NFC stickers instead).
  • v1 (a month): printed runes with JSON on the chip, Home Assistant actions, card printer.
  • v2: combining runes and spell duels.

Scores, v2

Novelty 9
Engagement 9
Feasibility 7

Compared with v1: a spell is now a portable physical object with its code inside, which brought in collecting, gifting, combining and duels.