Turn the Gears — Siena Griffiths

Overview

Turn the Gears is a hands-on exhibit game our five-person team designed for a children's museum Art Lab. Players guide a ball from a slot at the top of the board to a lit exit slot at the bottom by twisting rows of paddles to build a path before the ball is released — mirroring the engineering design process: plan first, then execute. Whether the ball lands or not, every player earns a station key to continue through the museum.

Two children playing Turn the Gears at the museum exhibit while a team member helps — Fig. 1 — The game in action at the museum's Art Lab.

How you play

A player picks a difficulty, which lights up three possible entry slots and one to three possible exits. A rotating hourglass marks the time they have to arrange the paddles by hand. When time's up, a servo releases the ball — and if it reaches a lit exit, an RGB strip lights up to celebrate. The twist-it-yourself paddles make the physics intuitive and satisfying across a wide range of ages.

Easy: Exit any of 3 slots · 3 minutes
Medium: Exit 2 set slots · 2 minutes
Hard: Exit 1 set slot · 1 minute

We deliberately gave more time than an engineering student would need — testing with real kids showed younger players needed room to learn the mechanic and work within their fine-motor skills.

See how to play & more →

How it's built

The design went through three prototypes. A ~15-inch cardboard low-fidelity model proved out the core mechanic — and revealed a problem: a square grid of paddles let the ball fall straight down without being redirected. The 30×35-inch high-fidelity build fixed that by staggering the paddles into a grid of equilateral triangles, so the ball is always turned by a paddle on its way down.

The final dry-run model added a clear acrylic front so players can watch the ball's path, a navy-painted MDF backboard, and custom 3D-printed lilac-and-teal knobs on every paddle. The board, paddles, and enclosure were designed in AutoCAD and laser-cut from quarter-inch MDF; the knobs and hourglass mounts were modeled in SolidWorks and 3D-printed.

The laser-cut board showing the staggered grid of paddles and the shaped entry and exit slots — Fig. 2 — The staggered paddle grid and shaped entry/exit slots, mid-build.

Under the hood

Each difficulty level runs on its own Raspberry Pi Pico microcontroller, mounted centrally with soldered, extended wiring that reaches across the full board. Per level: six LEDs mark the lit entry and exit slots, three 180° servos release the ball, three limit switches sense where it lands, a 360° servo flips the hourglass timer, an arcade button starts the round, and an RGB strip celebrates a win.

The back of the board showing the soldered wiring, servos, and limit switches — Fig. 3 — The wiring behind the board: servos, limit switches, and LED runs back to the Pico.

We programmed the Picos in MicroPython. A simplified excerpt from the hard-level round:

# HARD level — one lit exit, 60-second timer
set_servo_speed(forward_duty)      # flip the hourglass
time.sleep(60)                     # player's time to build a path

# release the ball, then watch the exits
for servo in (servo_1, servo_2, servo_3):
    servo.duty_u16(half_duty)

if rand_num_1 == 1 and response_1.value() == 1:   # ball hit the lit exit
    Light_Strip_On()               # celebrate the win

The reward keys

Every station also handed out a prize: small laser-cut plywood keys on keychains — roughly 60 per group across eight groups — so children collected a key at each exhibit as they made their way through the museum.

Plan first, then execute — the same design process we used to build it.

The team

A five-person team project, built with Ivy Lu, Toby Waller, Taylor Janson, and Maddie Carey.

Siena and a teammate with the Turn the Gears board during the build — Fig. 4 — Setting up during the build.