Prototype · October 2026

Two players influence a steel ball with EEG

Two players sit at opposite ends of a table, each wearing a single-channel EEG headset. A steel ball moves across the covered playing surface toward the player whose signal is currently less settled. The round ends when the ball reaches either end.

Beneath the cloth, a belt-driven linear axis moves a magnet under a clear acrylic sheet. The magnet pulls the ball along the surface; the mechanism remains hidden during play.

1steel ball
2black cloth over acrylic
3stepper motor
4magnet on the carriage
51000 mm linear slide
6six 5 cm risers

Player Arelaxation level relative to baseline

Player Brelaxation level relative to baseline

Simulated signals for two players. Drawn to scale. Part of the cloth is cut away in the drawing to show the slide underneath.

How it works

From headset to motor

HeadsetsEach player wears a battery-powered, single-channel EEG headset, with the electrode embedded in a head strap. The headset sends samples to the table's computer over its own Wi-Fi network.
SoftwareAt the start of a session, the software records a two-minute baseline for each player. During play, it compares each signal with that player's baseline and smooths the result over roughly ten seconds. The ball's speed and direction come directly from the difference between the two players' relaxation levels: the more relaxed player rolls the ball toward the less relaxed one, faster the bigger the gap.
Motion systemThe table's computer sends the target position over USB to a motor controller. A stepper motor moves a magnet along a linear rail beneath the acrylic, pulling the steel ball across the surface.

Parts

Parts list

Motion system8 items

Part	Qty
Belt-driven V-slot linear slide, 1000 mm, with NEMA 17 stepper motorone axis of a 3D printer; 880 mm of travel	1
TMC2209 stepper driver	1
100 µF capacitoracross the motor supply	1
12–24 V power supply, 2 A or morepowers the motor and driver only	1
Motor controller, Arduino Nano/Uno or ESP32receives the target position over USB; AccelStepper library	1
Limit switchhomes the carriage at start-up	1
Neodymium disc magnetsmounted on the carriage; two sizes, to test against the sheet and cloth	1 set
Jumper wires	1 set

Playing surface5 items

Part	Qty
Acrylic sheet, 61 × 122 cm, 5.6 mm thicksold as 24 × 48 × 0.22 in	1
Risers, about 5 cm tall3D-printed; at each corner and mid-span on each long edge	6
Washersset a 2–3 mm gap between the magnet and the sheet; the sheet rests on the risers unfastened	1 set
Black cloth	1
Steel ball, 25–50 mm	1–2

Headsets7 items

Part	Qty
BioAmp EXG Pill sensor boardone for EEG and one for ECG per player	4
ADS1115 analog-to-digital converter	2
ESP32 Wi-Fi board	2
Battery pack	2
EEG head band with dry electrodes	2
Spare headband kit	1
ECG snap electrodes	1 pack

Computer1 item

Part	Qty
Raspberry Piruns the game and its own Wi-Fi network, processes both players' signals and sends the target position over USB	1

Budget

Prototype budget

Parts

Group	Cost
Headsets: two, EEG and ECG, with batteries, plus a spare headband kit	$365
Computer: Raspberry Pi 5, power supply, memory card	$159
Electrodes: six gold cups, used dry	$27
Ball drive and surface: slide, motor, magnets, acrylic, cloth, ball	$230
Parts total	$781

Includes tax and shipping. Risers are 3D-printed in the lab.

Labor

Two builders, 30 hours combined, $30/hr. Code drafted with AI assistance, tested on the hardware.

Phase	Hours	Cost
Assembly: headsets, slide, motor wiring, surface, Pi	8	$240
Software: streaming, signal processing, motor control	4	$120
Sensor and mechanics tests: electrodes, magnet, gap, speed	8	$240
Relaxation measure: record sessions, compare EEG, HRV, breathing	5	$150
Tuning and playtesting: baselines, smoothing, two-player rounds	5	$150
Labor total	30	$900

Consulting

Role	Hours	Cost
R&D advising: Robert, $75/hr (reduced rate)	4	$300
Consulting total	4	$300

Summary

October 2026 · US dollars

Category	Cost
Parts: with tax and shipping	$781
Labor: 30 hours at $30/hr	$900
Consulting: 4 hours at $75/hr	$300
Total	$1,981

Timeline

Estimated timeline

About 2–3 weeks from approval. These are estimates; parts delivery sets the start.

Phase
Parts: order and receive; bench-test the dry electrodes meanwhile	1 week
Development: assembly, software, tests, tuning, playtests	1–2 weeks
Total	2–3 weeks

Development log

October 1Received the brief from Robert, with two proposed mechanisms: a tilting surface and a concealed moving magnet.
October 2Developed both concepts far enough to compare their dimensions, components and signal-processing requirements.
October 2Selected the concealed-magnet design as the primary prototype.
October 3Design spec update: moved the table to its own computer, a Raspberry Pi with its own Wi-Fi network, so it runs without a laptop. Gave the table its own pair of headsets, with dry electrodes and no paste.
October 5–7Priced each part from store listings and compared a smaller proof-of-concept build with the full version.
October 8Added ECG as a development tool: heart-rate variability helps us tune and check the relaxation measure. ECG may or may not be part of the final build. Set the budget at $1,981 across labor, consulting and parts.
NextOrder parts and begin assembly.

Constraints

Prototype constraints

Each headset is battery-powered and communicates with the table's computer over Wi-Fi. Players are not electrically connected to the table or motor supply.

The prototype is an experimental game interface, not a medical, diagnostic or wellness device. It uses our existing single-channel EEG hardware and signal-processing code.

MindWave Therapeutics 2026