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ConductorPepík’s Train

Figurine passengers board at the station, and the conductor, Mr. Pepík (Pepík is the Czech nickname for Joe), calls out the stops, cracks jokes and tells the little adventures of every passenger.

Ages 4–7 · no reading needed
Side view of the printed locomotive: red and black with gold trim, the smokestack doubles as an LED diffuser, a speaker in the roof, a XIAO ESP32S3 and a battery inside, two Hall sensors underneath facing the track, and a magnetic coupling to an open wagon carrying a cow figurine.

Take the train for a spin

How to play: pick a passenger (they wait on the main station platform), then move the train along with the “Go!” button. At their stop you can let them off, or let them oversleep. Station announcements that aren’t word for word from the concept are illustrative.

Who’s riding?

StationToot toot! The platform is empty. Who’s coming along?

The dragon with a cold

My 6-year-old puts the dragon on the platform. Dragon: “I’m off to the fire station. I’ve got a cold and I’m scared I’ll sneeze fire!”

She sits him in the wagon and pushes the train along.

The fire station stop: a siren, “AAACHOO!” and the engine flashes red.

Mr. Pepík calls out: “Firefighters, help! Our dragon is sneezing little flames!”

How to play

  • Our 6-year-old builds a wooden train track and adds printed stations (Bakery, Zoo, Firehouse, Forest, Grandma’s House). Each station’s track piece hides a code made of magnets.
  • On the main station (the only one with electronics) she places a passenger, a figurine with an NFC tag. The passenger says where they’re going and why.
  • She seats the passenger in a wagon and off they go. The engine reads each station’s magnetic code and Mr. Pepík makes the announcements.
  • At the right stop: “Mrs. Cow is getting off!” If a passenger rides past their stop: “Mr. Hedgehog, you overslept! We’ll go around once more.”
  • Every morning brings a new timetable: different stories, different wishes. Passengers can also be figurines from the Hatchery, another toy in the collection (an NFC UID is a shared identity across the toys).

Mrs. Cow goes out for a bread roll

S
Station(toot toot) “Mrs. Cow is waiting on the platform with her suitcase.”
C
Mrs. Cow“Moo, good morning! I’m off to the bakery for a bread roll. Just one, though. I’m on a diet.”

the train passes the Zoo

P
Mr. Pepík“Zoo stop! The monkeys are waving. Mrs. Cow, this isn’t your stop yet, please stay seated.”

Bakery

P
Mr. Pepík“Bakery stop! Mrs. Cow is getting off.”
C
Mrs. Cow“Yum. On second thought, I’ll have four rolls. Moo, these things happen.”

Why a tenth time

A new timetable and new stories every day. A collection of passengers (you keep printing more figurines: a dragon, a cow, a hedgehog, a granny on a scooter) and combinations, because two passengers in the same train chat and bicker. Kids come up with their own routes, since the order of the stations changes the story. A wooden railway is a toy little kids keep playing with for years.

What AI adds

An ordinary talking toy train has ten fixed phrases. Here Claude writes a new timetable with hundreds of lines every night, covering every combination of passengers, stations and order, with humor for 4-year-olds.

The game itself stays offline and has no microphone, so the child never talks to the AI.

10fixed phrases in an ordinary train
100sof lines in the timetable, new every night

How it’s built

  • Locomotive ~110 × 40 × 60 mm, a profile that fits standard wooden tracks, MMU red + black + gold, the smokestack doubles as an LED diffuser, a speaker in the roof. A magnetic coupling for the wagons.
  • Wagons: 2–3 open cars with a recess for a figurine.
  • Stations: a 150 mm track piece with a building, and inside the track 1–3 magnets at coded spacing (inserted during a print pause). The buildings have big icons and no text.
  • Main station ~200 × 120 mm with a platform (the reader sits underneath) and a clock.
  • Passengers: ~45 mm figurines (bigger than the small-parts test cylinder), with an NTAG213 sealed into the base.

Electronics — bill of materials

PartWhat forPrice CZKSource
XIAO ESP32S3 (loco)playback, state269electronics notes, section 4
MAX98357 + 28 mm mini speakerthe train’s voice98 + ~40 (estimate)#48
2× linear Hall SS49Ereading station codes~20 (estimate)—
LiPo 400 mAh + TP4056loco battery~120 (estimate) + 20—
WS2812 ×2smokestack, flashing~20 (estimate)—
ESP32-S3 DEVKit (station)station, sync448electronics notes, section 4
RC-522reading passengers49#30
MAX98357 + 40 mm speakerstation voice187#48, #50
NTAG213 ×8passengers96#31
Total (about €55)~1,370 CZK

Architecture

At night (the Gateway)

Claude → timetable {passenger × destination × station × order → lines}; a parent can look it over
Piper → MP3
over Wi-Fi into the flash memory of the loco and the station

Play (offline)

the station reads the passenger’s NFC tag → ESP-NOW → the loco knows who’s on board
loco: Hall sensors read the station code
state machine (who’s going where) → plays the MP3

The boundary: a state machine in the code decides what gets said and when. The model only writes lines into a template of situations, overnight.

Safety and offline

Always offline during play: no microphone, no camera. Magnets and NFC tags are fully enclosed, and the battery sits under a screw-down lid. Figurines and wagons are bigger than the small-parts cylinder, but it’s still ages 4+ only (not for siblings under 3). The volume is capped in code.

Build timetable

Protofirst playable · a weekend
The engine + 3 magnet stations, pre-generated announcements, no passengers yet.
v1The main station and NFC passengers, a fresh timetable every night.
v2Several passengers at once chatting with each other, Hatchery figurines as passengers.
7novelty
9engagement
8feasibility

Compared with the version from the Engineer (one of the two AI agents that came up with the ideas), this one adds figurine passengers and a station, so the child invents routes, collects characters, and the humor has real heroes.