Hardware · build

A 3D-printed marble clock that scrolls text

Marble clocks are well explored, so one maker asked what happens when you swap digits for a scrolling text wheel. Black and white marbles, a lot of 3D printing and a lot of retries.

Build sheet

Drive: Stepper motors (wheel + selector)
Sensing: IR sensors
Body: 3D-printed, bolted
Marbles: Black and white steel balls

Can I build this?Advanced · AI 3/5 · $150–300

Difficulty: Advanced
AI-buildability: 3/5
Time: A month or more
Cost: $150–300

Parts

Stepper motor IR sensor Steel ball bearings PLA filament

Tools

3D printer

Starter prompt

Based on "A 3D-printed marble clock that scrolls text" on Afterware: https://afterware.xyz/p/a-3d-printed-marble-clock-that-scrolls-text

Write Arduino firmware for an ESP32 that drives two stepper motors through a TB6600 or similar driver: one rotates a ring of marble channels, the other moves a selector arm. Use two IR sensors to detect the home position on the wheel and the selector. Given a text string, convert each letter to a sequence of black and white marble slots, then step the wheel so each slot receives the correct color.

Estimates based on the original write-up. How AI-buildability is scored. Building with an AI assistant? Connect it to Afterware (free MCP server).

Story

Marble clocks show time with fixed digits. Ivan Miranda wanted text with no digit limit, so the build became a big round wheel of marble channels. Inner steel ball bearings drop black or white marbles into the slots, and the wheel's stepper motor lines up each channel. A second stepper on an inner selector picks the right color for each slot, so the wheel builds the target sequence one marble at a time.

The whole structure is 3D printed and bolted together, and it's a big one. It took several rounds of trial and error, including IR sensors that got confused by daylight. It now mostly works. The wheel still has to be homed by hand before each run, and the black-to-white ratio can leave gaps in the final text. The text is still legible, and the scroll never runs out of room.

Resources · 1

Build video