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YOU CAN BUILD A PLATE THAT TURNS SOUND INTO PERFECT SAND PATTERNS

Sprinkle sand on a metal plate, play a tone, and watch chaos snap into perfect symmetric figures — 240-year-old physics you can build in an afternoon.

by Aron Hoekstra (guide) / Ernst Chladni (physics)

FULL CAD BOM FIRMWARE DOCS

SciencePhysics

Built withArduino

difficulty
●●○○○
time
an afternoon to a weekend
license
not specified
repo
repo STUDENT PROJECT; GUIDE LIVES ON INSTRUCTABLES1 stars
Videos
1
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COMPAREE VERDICT

This is one of the simplest and most mesmerising builds around: a steel plate sprinkled with salt, driven by a tone, and the grains leap into symmetric figures along the silent nodal lines — Ernst Chladni's 18th-century experiment, running on your table. There is no GitHub project here. The best guide is a 6-step Instructables by a dad whose son took first place at a science fair with it, and its central insight is what NOT to do — do not tear apart a speaker to make a "wave driver" (he ruined one trying). Instead an unmodified subwoofer pushes a threaded rod that carries the plate, and a free online tone generator does the rest. If you want the electronics version, a Brazilian engineering-school team published amplifier schematics and Arduino firmware — including the lesson that a little LM386 module cannot shake the plate hard enough.

GOOD TO KNOW

  • —Honest up front: there is NO real open-source repo for this build — it is a classic physics demonstration, not a maintained project
  • —The best build guide is on Instructables (6 illustrated steps, complete parts list in step 1) — that is what our page follows
  • —The only GitHub hardware attempt we found is a Brazilian student project (IFSP São Paulo) with amplifier schematics, PCB layouts and Arduino firmware — but it declares no license
  • —Most of the GitHub repos named "chladni" are software simulations of the patterns rather than build plans.
  • —No 3D printing involved — this is sheet metal, threaded rod and a subwoofer

Parts to buy

6 items

From our check of the build. Exact quantities and part numbers are in the creator’s BOM.

  • Steel plate (about 18 inches square)Find
  • Unmodified subwooferFind
  • Amplifier with aux inputFind
  • Threaded rods and nutsFind
  • Acrylic sheetFind
  • Table saltFind

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Can I build this?

Printnothing — this build is sheet metal and hardware-store parts, no 3D printer involved
Buya steel plate (about 18 inches square), an unmodified subwoofer, an amplifier with aux input, threaded rods and nuts, an acrylic sheet, table salt
Toolshacksaw for the rods, drill (one hole dead-centre of the plate), metal shears, audio cable
Skillsbeginner — measuring, cutting and drilling; the physics does the impressive part
Timean afternoon to a weekend
Costband $ — mostly hardware-store parts plus a speaker and amp many people already own
Safetyloud low-frequency tones for extended periods — protect your hearing; cut sheet-metal edges are sharp; you can destroy a speaker by overdriving it

Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.

Videos

Chladni Figures — random couscous snaps into beautiful patterns3:50

Steve Mould's demo — the clearest explanation of why the grains find the silent lines.

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Gallery

The finished rig — plate on rod on subwooferAron Hoekstra / Instructables
Everything you need, laid outAron Hoekstra / Instructables
Salt on the plate, pattern formingAron Hoekstra / Instructables
A symmetric figure locked inAron Hoekstra / Instructables
A more complex mode at higher frequencyAron Hoekstra / Instructables
The IFSP class-AB amplifier schematic — for the electronics routeP07Bueno / IFSP São Paulo

Start here

Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.

  1. 1.Follow the Instructables guide (6 steps with pictures; parts list in step 1)
  2. 2.Watch Steve Mould first (you will understand what you are building)
  3. 3.Use an online tone generator (the guide's own recommendation — no electronics needed)
  4. 4.Electronics route: the IFSP repo (amplifier schematic, PCB, Arduino DDS firmware — no license declared)
  5. 5.More background: the Make: article (the classic wave-driver approach (harder))

Resources

Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.

KNOWN ISSUES

  • Do NOT dismantle a speaker to build a 'wave driver' — the guide's author ruined one and never got it working; his whole design exists to avoid that
  • Plate thickness is critical: too thin sags and the salt slides off; too big is too heavy to vibrate — around 18 inches square hit the sweet spot
  • Start with the volume LOW — too loud and all the salt jumps straight off the plate
  • There is no universal magic frequency — it depends on your plate's material and size (the guide found 80–250 Hz; the IFSP team's smaller plate resonated at 190–340 Hz). Sweep slowly and watch
  • The rod-to-speaker joint is the weak point — tape worked on a hard plastic cone; soft paper cones need another approach
  • It gets messy — put the whole rig in a large box lid before you pour the salt

Why does the sand form patterns?

The tone makes the plate resonate in standing waves. Most of the plate vibrates violently and throws the grains around — but along the nodal lines the plate stands still, so the grains settle there. The pattern is literally a map of the silence.

Is there any open-source repo for this?

Not really: most GitHub "chladni" repos are pattern simulations. The hardware exception is a Brazilian student project (IFSP) with amplifier schematics and Arduino firmware — useful, but it has no license. The best build guide is on Instructables.

Does it have to be salt on steel?

No. Salt, fine sand and cornmeal all work (the IFSP team lists all three), Steve Mould uses couscous, and the plate can be steel or even polypropylene. You just need fine grains with good contrast — spraying the plate black helps.

Can I drive it from an Arduino?

Yes, but not naively: the tone() function makes a harsh square wave, and a bare LM386 module is too weak to form clear patterns. The IFSP project solved both — a DDS sine generator on the Arduino plus a ~1.5 W class-AB amplifier, with schematics and firmware in their repo.

Community builds

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Discussion1

FROM THE COMPAREE TEAM

The guide found its patterns between about 80 and 250 Hz with a subwoofer, but a different plate or speaker will resonate elsewhere. What frequency range would you start sweeping first?

CompareeTEAM2mo agoedited

Practical notes from our verification: Aron Hoekstra's Instructables guide has six steps plus an intro, a materials list and a results section with a video and photos of the patterns. It uses an unmodified 8-inch subwoofer, a guitar amplifier, a free online tone generator and an 18-inch square of sheet metal bolted to a threaded rod that rests on the speaker cone. The guide gives a working range of about 80 to 250 Hz for this setup and advises starting around 100 Hz with the volume low. It does not specify a sheet metal gauge beyond 'stiff enough not to sag', so plate choice is where your build will differ. A box around the rig makes cleaning up the salt much easier. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.

You can build a wall of 80 steel balls that float and ripple like liquid metal

●●●○○ · another mesmerising physics display, much bigger build

You can build a wall of liquid magnet that draws animations in mid-air

●●●●○ · liquid instead of sand, electronics instead of tones

You can build your own floating ring of plasma in a glass sphere

●●●●○ · the high-voltage end of beautiful physics

Aron Hoekstra (guide) / Ernst Chladni (physics)

A dad and his son built an easy version for a school science fair — first place — and wrote it up on Instructables in 2015, including the failed speaker-modding attempt that led to the simpler design.

Web

Star the project on GitHub

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  • Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
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