Tabletop prototype · October 2026

Two players. One steel ball.
Brain rhythms move it.

Two people sit at either end of a small table, each wearing a light one-sensor headset. Underneath a black cloth, a single motorised axis from a 3D printer carries a magnet in place of a print head, and the steel ball on top follows it. The ball drifts slowly toward the player whose brain rhythms are less settled. When it reaches one end, the game is over.

Player Ahow settled
Player Bhow settled

Simulated players, drawn to scale in centimetres. A strip of the cloth is cut away to show the slide underneath. In the real build the cloth hides everything, and people only see the ball moving on its own.

How it works

Three parts, one wireless link

  1. HeadsetsEach player wears a single sensor at the back of the head. It reads brain rhythms and sends them over Wi-Fi, running on its own small battery.
  2. Game softwareA laptop compares the two players against their own two-minute warm-up, smooths the signal over about ten seconds, and works out where the ball should go.
  3. Hidden axisThe laptop sends the ball's position over USB to a small motor board, which slides the magnet along the 3D printer axis under the acrylic. The ball follows, slow and steady.

Parts list

What goes into the first prototype

Moving the ball

  • 1Belt-driven V-slot linear slide with a NEMA 17 stepper motor, 1000 mmone axis of a 3D printer, with about 88 cm of travel
  • 1TMC2209 stepper driverthe quiet one: near-silent movement suits a calm game
  • 1100 µF capacitor across the motor supplystandard with the TMC2209
  • 112 V or 24 V power supply, 2 A or morefor the motor only, separate from everything the players wear
  • 1Arduino Nano or Uno, or an ESP32moves the motor smoothly with the AccelStepper library
  • 1Limit switchhomes the carriage when the table starts up
  • 1 setStrong neodymium magnetson the carriage, in place of the print head
  • 1Jumper wires

The playing surface

  • 1Clear acrylic sheet, 24 × 48 in, 0.22 in thick
  • 6Risers, about 2 in tallone per corner and one mid-span on each long edge, so the sheet doesn't bow: rubber feet, wood blocks or PVC caps
  • 1Washersfor fine-tuning: the sheet sits 2–3 mm above the top of the magnet and simply rests on the risers
  • 1Black clothcovers the sheet and hides the mechanism
  • 1Steel ball, 1–2 in

Two headsets

  • 2BioAmp EXG Pill sensor boards
  • 2ADS1115 signal converters
  • 2ESP32 Wi-Fi boards
  • 2Battery packs
  • 2Headbands with gold-cup electrodes and ear clips
  • 1Conductive EEG paste

Running the game

  • 1Laptopprocesses both headsets' signals and sends the ball's position to the motor board over USB

Progress

From brief to build plan in two days

Built with care

Safe, simple, honest

Battery-powered headsetsThe headsets run on their own batteries. Wi-Fi is the only link between a player and the table.

A game, not a testIt's an expressive game played with brain rhythms. It makes no health or wellness claims.

Built on our own toolsThe headsets and signal code come from our own one-channel EEG design, already in progress.