Open Source • Built by a Dad • Powered by ESP32

M.A.S.S. TRAPMotion Analysis & Speed System

A forensic-grade physics laboratory disguised as a Hot Wheels track speedometer. Microsecond timing. Evidence chain of custody. Full web dashboard. All running on a $7 microcontroller.

🎮 Try the Live Demo Build One View on GitHub Download Firmware
35,000+
Lines of Code
$7
Hardware Cost
µs
Timing Precision
58
API Endpoints
2
External Deps

What Is This Thing?

Everything you need to run a real physics experiment with toy cars.

⏱

Microsecond Race Timing

Hardware interrupt-driven timing on dual-core ESP32-S3. IR break-beam sensors at start and finish. No polling, no missed events, no excuses.

📊

Full Physics Dashboard

Speed, velocity, momentum, kinetic energy — calculated in real-time and served over WiFi. Five visual themes. Works on any browser.

🔒

Evidence Chain of Custody

Every race gets a case number, QR-coded evidence tag, and printable label. NFC stickers auto-identify cars. Forensic-grade data logging.

🎓

Science Fair Mode

Guided 6-phase workflow: define variables, intake vehicles, collect data, and generate reports. One button = full science fair submission.

📡

ESP-NOW Mesh Network

Up to 3 devices communicate wirelessly: start gate, finish gate, and mid-track speed trap. Microsecond-synced clocks. Auto-discovery.

🎧

Audio Announcer

Built-in I2S audio calls out race results, car names, and speed records through a speaker. Your track talks back. No external apps needed.

💡

WLED LED Integration

Sync addressable LED strips to race state. Armed = breathing blue. Racing = chase animation. Finish = celebration burst. 1000+ LEDs supported.

📱

NFC + LiDAR + OTA

NFC stickers on cars for auto-identification. TF-Luna LiDAR for auto-arming. Browser-based firmware updates. No cables needed after first flash.

Ryan Says
This started as a weekend project for my son's science fair. Two months and 21,000 lines of code later, it's a full forensic physics lab that runs on hardware cheaper than the Hot Wheels cars it measures. If a 10-year-old can operate it, so can you.
SCIENCE FAIR 2026
🔬 Laboratory Evidence Report
49 experimental runs • 4 test subjects • Chrome steel spheres & Hot Wheels F-150s
Effect of Mass on Velocity in a Gravity-Driven System
📄 View Full Lab Report

Live Dashboard Preview

This is the actual dashboard UI. No hardware needed — watch it run a simulated race.

🎨 Switch Theme:
👇 Click the buttons! ARM a race, pick a car, try all 5 themes.
🚨 DEMO MODE

M.A.S.S. TRAP

MOTION ANALYSIS & SPEED SYSTEM
COMMAND CENTER
LINKED
AWAITING SUSPECTS
Time
--s
Real Speed
--mph
Scale Speed (1:64)
--mph
Momentum
--kg·m/s
Kinetic Energy
--J
Total Runs
0
MOST WANTED
Waiting for race data...
CASE FILE
RunSuspectMassTimeReal MPHScale MPHMomentumKE
No evidence recorded yet
SCIENCE FAIR MODE
✓
Setup
✓
Intake
✓
Evidence
✓
Pre-Flight
5
Collect
6
Results
▶ PHASE 5: DATA COLLECTION
Collecting race data with sanity checks. Auto-advancing through test matrix.
Run 0 of 20
THE GARAGE
Click a car to select it for the next race
FORENSIC ANALYSIS
v = d / t
Velocity
-- m/s
6.01m ÷ --s
p = m × v
Momentum
-- kg·m/s
--kg × --m/s
KE = ½mv²
Kinetic Energy
-- J
½ × --kg × --²
a = v / t
Acceleration
-- m/s²
--m/s ÷ --s
FW v2.6.0-beta
What You're Seeing
This is a fully interactive simulation of the real dashboard served by the ESP32. The actual system uses WebSocket for real-time data — this demo runs the same UI with simulated race data. Click ARM to run a race manually, or just watch it auto-cycle.

Build Your Own

Pick your budget. Get the parts. Flash the firmware. Race.

Starter Track
~$25 estimated
Minimum viable speed trap
  • ESP32-S3-WROOM-1 N16R8 — the brain ($7)
  • 2x IR break-beam sensors — start + finish detection ($4)
  • Breadboard + jumper wires — no soldering needed ($5)
  • USB-C cable + power — phone charger works ($3)
  • Hot Wheels track + car — any track, any car ($6)
  • WiFi dashboard with timing and speed
  • CSV data export for science fair
View Parts List
Ryan Recommends
Science Fair Ready
~$60 estimated
Everything Ben used for his project
  • Everything in Starter, plus:
  • Milligram scale — weigh cars to ±0.001g ($12)
  • NTAG213 NFC stickers — scan car, auto-select ($5/50pk)
  • Tungsten weight set — add mass for experiments ($10)
  • MAX98357A I2S amplifier — audio announcer ($4)
  • Small speaker — 3W, 4 ohm ($3)
  • Evidence tags with QR codes
  • Auto-generated science fair report
  • Guided 6-phase testing workflow
View Parts List
Full Send
~$120 estimated
The "it's 3am and I can't stop" build
  • Everything in Science Fair, plus:
  • 2nd ESP32 — dedicated start gate ($7)
  • 3rd ESP32 — mid-track speed trap ($7)
  • TF-Luna LiDAR — auto-detect cars at start ($12)
  • BTF WS2812B LED strip — 1000 LEDs of drama ($20)
  • WLED controller — separate ESP32 for lights ($7)
  • 3-device ESP-NOW mesh network
  • LiDAR auto-arm (hands-free operation)
  • Synchronized LED race animations
  • Mid-track velocity measurement
View Parts List
Links to Amazon and other retailers may include affiliate tags. This costs you nothing extra and helps support the project. We only recommend parts we've actually used and tested. No sponsorships. No bullshit.

Build Wizard

Tell us what you want to build. We'll tell you exactly how to wire it.

🔌 Open the Build Wizard
🔌

Interactive Build Wizard

Pick your module. Follow color-coded wiring diagrams step-by-step. No schematic reading required. No electronics experience needed. First module live now: Onboard Telemetry (XIAO + BNO055).

Step 1: Pick your module
Step 2: Follow the color-coded wires
Step 3: Flash firmware & verify
Did You Know?
Galileo proved that all objects fall at the same rate in a vacuum in 1589. But on a real track with friction and air resistance, heavier objects have more momentum to push through. That's exactly what M.A.S.S. Trap measures — the difference between theory and reality.

Browser Flasher

No software to install. No command line. Just plug in and click.

⚡

ESP Web Flasher — Coming Soon

Using ESP Web Tools, you'll be able to flash M.A.S.S. Trap firmware directly from this page. Select your build configuration, connect your ESP32 via USB, click Flash. Done. Works in Chrome and Edge.

Project Roadmap

What's built, what's next, and what's cooking at 3am.

✓

Core Race Timing

Microsecond ISR timing, physics calculations, CSV logging, web dashboard

✓

ESP-NOW Mesh Network

3-device communication: start gate, finish gate, speed trap. Auto-discovery and clock sync.

✓

Evidence System + NFC

Case numbers, QR evidence tags, NFC stickers for car ID, printable labels, chain of custody.

✓

Science Fair Playlist Mode

6-phase guided workflow: experiment setup, vehicle intake, evidence prep, pre-flight, data collection, report.

✓

Browser Firmware Update

OTA updates from GitHub with MD5 verification. No cables after first flash.

✓

Audio Announcer + WLED

I2S audio playback, race result announcements. WLED integration for LED animations.

✓

Interactive Build Wizard

Pick your module, follow color-coded wiring diagrams step by step. First module: Onboard Telemetry.

⚙

Parts Store + Affiliate Links

Curated component lists by budget tier with current Amazon pricing.

☆

Drag Tree Start Gate

Christmas tree countdown lights + servo-controlled launch gate. Full drag strip experience.

☆

Onboard Telemetry

XIAO ESP32-S3 + accelerometer strapped to a Hot Wheels car. G-force, vibration, real-time radio.

☆

LTI Integration

Connect to Moodle/Canvas as an external tool. Auto-submit science fair data for grading. $7 board does what $10K LMS can't.

“This project was built at kitchen tables and workbenches between the hours of midnight and sunrise. A dad, his two sons, and an AI — proving that the best tools in the world are worthless without the people willing to stay up all night using them.”
— The Special K Report™

💬 Join the Discussion

Building your own? Got ideas? Just want to say something nice? Drop a comment or reaction below. Every message lands in our GitHub Discussions.