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Toy Workshop · round 2An ice rink at the kitchen table
An add-on for the table hockey you already play at home

Goal Sirenfor šprtec table hockey

Our šprtec (Czech table hockey played with flat round pieces, a small puck and a stick) gets goals that know when someone scores: they light up the scoreboard in the team’s color and sound a siren. In the full version, a phone instantly replays the goal in slow motion.

Whoour 9-year-old with Dad, the whole family
Wherethe kitchen table
How longa 10–15 minute match, a weekend tournament
Build~350 CZK (about €15) · ~8 h of printing · one evening of soldering

What’s new: the only toy in the set that upgrades a game the family already owns. Everyone knows the rules, so the magic works from minute one. It plays without a Mac or a network.

Šprtec table hockey with the goal siren At the top, a scoreboard with an LED ring, a clock display showing 1:0 and the crests of Barcelona and Florec. Below it, the šprtec rink seen from above with two goals. An IR beam runs across each goal 15 mm behind the goal line, and a thin wire runs from each goal to the scoreboard. 1 2 3 4 5 6 7 8
  1. 1Scoreboard and team crests: printed, crests in MMU colors
  2. 2WS2812 LED ring with 8 LEDs, lights up in the team’s color
  3. 3TM1637 clock display showing the score
  4. 4Inside the scoreboard: ESP32-C3 and a piezo siren
  5. 5Goal v2 (printed) with a channel for the beam
  6. 6IR beam 15 mm behind the goal line
  7. 7Thin wire, runs only to the beam
  8. 8Puck 18 × 6 mm, pieces Ø 30 mm
printed partselectronics
Live

A match on the kitchen table

Shoot for Barcelona (big brother) or Florec (little sister). A goal only counts when the puck breaks the IR beam inside the goal. If the goalie makes the save or the puck hits the post, the scoreboard stays quiet. Sound plays only after you click. Here, chance decides who scores; on the real table, the stick does.

Barcelona
Big brother
match time 0:00
Florec
Little sister
Slow-motion replay · last 5 s

The IR beam is the red dashed line in each goal; the orange blocks are the LED and the phototransistor.

Mode Sound

Trainer: you get ten seconds for each goal. The countdown starts with your first shot.

Announcer

Face-off. The scoreboard is waiting for the first shot.

Match log

Season on the scoreboard

TeamWinsGoals
Barcelona00
Florec00

Fastest goal of the season: none yet.

The slow-motion replay belongs to the full version: an old phone above the rink keeps the last five seconds in memory, and when a goal is scored the scoreboard signals it to play them back.

Face-off

The first 30 seconds and why a tenth time

0:30

The first 30 seconds

My 9-year-old sends the puck with his stick between his sister’s pieces and into the goal. The puck crosses the beam inside the goal, the LED ring on the scoreboard lights up in Barcelona’s colors, the siren sounds and the score jumps to 1:0.

10×

Why a tenth time

The goal ritual and the score turn a kitchen game into a real match. The scoreboard keeps track of the season (wins, goals, fastest goal), and the trainer gives you ten seconds per goal. In the full version, the slow-motion replay settles every “was that a goal?” argument.

Roster

Printing, electronics and AI

Printing

Goals v2 and scoreboard

Goals v2 based on my sprtec_goal.scad, with a channel for the beam. The inside keeps the official 80 × 50 × 48 mm of the current goal.

A scoreboard with one LED ring and team crests printed on the MMU (Barcelona and Florec already exist as printed teams).

Electronics

Beam and scoreboard

In each goal, an IR LED and a phototransistor sit about 3 mm above the floor and 15 mm behind the goal line. The 18 × 6 mm puck breaks the beam; neither the stick nor the goalie can reach that far.

In the scoreboard: an ESP32-C3, the LED ring, a piezo siren and a clock display for the score.

AI

Optional only

A commentator working from a pre-generated bank of lines. Claude writes the lines ahead of time in the workshop; the scoreboard just plays them.

Printing and electronics carry the toy. It works fully without AI.

Code decides

A goal is a broken beam, nothing else. The score, the ring color, the siren, the season and the trainer countdown all run on the ESP32-C3 in the scoreboard, with no Mac and no network.

The model decides nothing

No model gets called during a match. It writes the commentator’s lines in the workshop beforehand, and only for the optional add-on.

Side view of the goal: the beam 3 mm above the floor and 15 mm behind the goal line; the puck breaks it SIDE VIEW · SCHEMATIC goal line puck 18 × 6 15 mm 3 mm goalie stick beam across the goal Top view of the goal: IR LED on one side, phototransistor on the other, the beam across the goal 15 mm behind the line TOP VIEW IR LED phototransistor net line

The whole trick is where the beam sits. At 3 mm above the floor, a 6 mm tall puck always breaks it, and 15 mm behind the line neither the stick nor the goalie can reach it. That’s why the wire from the scoreboard only runs to this beam.

Lineup

First playable prototype

A scoreboard with an ESP32-C3 and one LED ring, plus two goals on a thin wire that runs only to the beam. It plays without a Mac or a network.

Printing ~8 hSoldering one eveningCost ~350 CZK (about €15)Power a phone charger
PartWherePrice sourceCZK
ESP32-C3 Super MiniscoreboardLaskaKit148
2 pairs of IR LED + phototransistorgoalsestimate~20
WS2812 LED ring, 8 LEDsscoreboardestimate~50
Piezo sirenscoreboardestimate~10
TM1637 clock displayscoreboardLaskaKit34
Wire and connectorsto the goalsestimate~30
Filament (goals v2, scoreboard, crests)printingestimate~60
Sum of the rows (the design card says ~350 CZK)~352

Overtime

Full version: slow-motion replay

An old phone on a stand above the rink keeps the last five seconds of video in memory, and when a goal is scored the scoreboard signals it to play them back. Nothing gets saved unless a player presses “save”.

The only extra part is a printed stand. Whether a particular phone can handle it still needs testing.

2 min

Penalty box: what to watch out for

Stats

Jury scores

“The best value in the whole pool: one evening of work buys an instant goal ritual for a game the family already has.”Jury, round 1: first place out of 48 ideas

“Score unchanged. The minimal version got cheaper, down to ~350 CZK, and the parts list adds up to the total. The video referee rightly stays in the full version only.”Jury, round 4

“No idea got a STOP.”No safety objection