GOK GOK

A pull-along hen that shows a child how a mechanism works. One egg at a time.

gok gok — Danish, slang

What you say when someone isn’t thinking straight, as if something is missing up top. This hen is the opposite: it wears its brain on the outside, so a child can see exactly how it thinks.

Context
SDU · ID2 · Spring 2025
Role
Solo — concept, CAD, prototype
Duration
4 days, brief to prototype
Prototype
Built in 24 hours
Tools
CAD · cardboard · plexi
E EGG INA PLEXI SHELL ×2B STAR WHEEL, 4 SLOTSC DRIVE PIND WHEEL + DRIVE DISCF EGG OUT, BEHIND
Fig. 00 — GOK GOK, side elevationDrop an egg in on top. Pull. Every quarter turn, one drops out behind.
01 — The brief

Design a pull-along toy. That was the whole brief.

I didn’t want to make something that only rolls. Most mechanics around us are hidden behind plastic, and children never get to see cause and effect. I wanted a toy that shows it — and that a parent would rather leave on the shelf than hide in a box.

Fig. 01 — Four-slot Geneva drive, redrawn from my CAD, running
02 — The mechanism

The wheel turns all the time. The star only moves a quarter turn at a time.

  1. 1Pulling the hen turns the wheel and the drive disc with it.
  2. 2Once per turn, the pin catches a slot and pushes the star 90°.
  3. 3Each step lets one egg fall out. Between steps, the star is locked.

The same principle has indexed film projectors and watch movements for a century. Here it’s big enough to watch.

03 — Form from mechanism

I didn’t design a hen and then fit a mechanism inside. The mechanism already was the hen.

A Geneva drive is three circles, two axles and one pin. I kept those shapes and added as little as possible: a head, a comb, a tail.

A — Three circles. The pin sits where two of them cross.
B — Cut them, and they become the drive.
C — Add a head, comb and tail. Nothing else.
Pencil sketches on black paper: the Geneva star and an early, rounder hen
Sketch — organic hen around the star wheel
Pencil sketches on black paper: the hen reduced to circles and a crank
Sketch — reduced to circles
04 — 24-hour prototype

24 hours. One question: does the idea survive the floor?

The finished design is clear plexiglass shells around metal parts, so a child can watch everything move. For the first prototype I chose speed over finish: wooden internals, one plexi half, one cardboard half. Enough to pull it across a floor and see what happens.

Top view of the prototype held by a hand: plexi shell, wooden star wheel and drive disc bolted togetherThe prototype on the floor seen from the front, pull rope attached at the beak
05 — What didn’t work

The egg dropped. Just not every time.

Problem 1 — Grip

The wheels slid on the wooden floor, so the drive skipped steps. A Geneva drive only steps if the wheel really turns. Grip is part of the mechanism.

Problem 2 — Balance

It couldn’t stand on its own. One axle is a line, not a base. It tipped as soon as I let go of the rope.

06 — Flat-pack

Every part is a flat profile. Cut from sheet, held by four rods.

That keeps production simple, and an older child can build it themselves — which teaches more than the toy does.

Shell ×2 — plexiStar wheelDrive disc + pinWheel ×2Head · comb · tailRod ×4
07 — Next version
01Laser-cut plexi shells and metal internals, as designed.
02Rubber on the wheels, so every pull becomes a step.
03A tail that reaches the floor, so it stands on its own.
04Put it in front of real children and watch what they do.