The cart you can get
Loaded KMJ beach cart on balloon tires at the waterline

A heavy-duty motorized beach cart

Patent pending

Drive it from the remote. No handle.

Same welded aluminum frame as the cart in the videos — two 3,000 W motors, balloon tires, built in the shop. The follow-me brain stays off this version. Every production cart carries a serial number and is tested before it ships.

New deposits are paused while pricing is updated. Existing deposits stand exactly as agreed. Join the list and you will hear the new price first. From Maine to New Jersey I deliver every cart myself; outside that range the cart ships freight, and the battery ships to you direct from the manufacturer.

160 lb
Total weight
400+ lb
Payload
4.5 mph
Top speed
Up to 30 mi
Range per charge

Store-bought electric beach wagons keep you on the handle: the motor helps, you steer by muscle. This one is remote-controlled. You walk free. The cart goes where you point it.

The design is patent pending — U.S. provisional filed August 2026. The full self-driving cart from the videos is not for sale. This is the version I can build now.

FrameWelded 6061 aluminum, 1.5" square tube, 32" × 48" deck. Built 2022. The frame has never changed.
Weight160 lb total. Complete cart, no cargo.
Payload400 lb — demonstrated on camera with five 80 lb roof-shingle bundles, not claimed on a spec sheet.
Speed~4.5 mph. Reverse about half that.
RangeUp to 30 miles per charge — measured on the cart, not estimated.
DriveTwo 3,000 W motors, one per rear wheel. #40 chain, 10:1 two-stage jackshaft — designed to climb steep inclines.
ControllersDual motor controllers with closed-loop speed control — the cart eases in and out of power instead of lurching, even loaded.
SteeringTwo kingpin pivot points on a fixed U-shaped steel support. 24V industrial servo. No front axle.
Wheels16.5" PU balloon tires urethane-bonded to two-piece carbon-fiber printed hubs. 2–4 psi; 2.5 psi for soft sand.
Battery24V 50Ah (1.3 kWh) LiFePO4, mounted under the frame — the heaviest component rides below the deck, not on it.
ControlHandheld RC transmitter. No Pi. No follow-me. No lidar.

Auto-Cart: it follows you

It began with a familiar problem: a mountain of beach gear and soft sand. The answer became a full engineering project — a welded aluminum cart on balloon tires. Then a wearable UWB tag and four corner receivers so the cart drives itself, with a 360° lidar and a six-sensor TFmini ring for obstacle sensing.

Seen it on TikTok? That’s this cart. Watch the follow-me video →

More films — the full build story and how the follow-me system works — on YouTube → @KMJDynamics

01

Follow-me

A wearable UWB tag and four corner receivers fix your position; the cart drives itself to you, hands-free.

02

Sees & avoids

Obstacle sensing uses a 360° lidar and a six-sensor TFmini ring.

03

Manual RC

Flip the switch on the remote and take over instantly.

04

Built for sand

Balloon tires and a welded aluminum frame float over loose sand instead of digging in.

Under the hood

Power

Built to survive its own motors

After a voltage spike destroyed the main computer, the power system was re-engineered: distributed, surge-protected supplies.

Control

Smooth, not lurching

Closed-loop speed control — predictable motion that eases in and out of power, even loaded.

Autonomy

No maps, no GPS

A wearable beacon fixes the operator. A 360° scanner flows the cart around obstacles in real time.

Telemetry

Watch it from a phone

Voltage, current, and charge state on a private dashboard — from across the beach or across the country.

Wheel hubs

The stock hubs developed play under motor torque. Each hub now prints as two identical halves in carbon-fiber nylon that lock into one solid body.

The KMJ Dynamics way

An independent shop with no blueprint handed down. Welded frames, custom power electronics, and autonomy code all come off the same bench — driven by one habit: keep building until the idea works in the real world.

Want it bolt by bolt? Get the Build Guide →

Next to the others

Their published numbers. Ours from the spec sheet.

KMJ RCe-Beach WagonSandhopperLitefar B1 new 8/18
DriveRemote. No handle.Handle + thumb throttleHandle + throttleHandle. Optional remote.
Gearing10:1 jackshaft · 130 N·m at the wheels (logged)Transaxle (53 N·m listed)Transaxle (ratio not listed)Hub motors (36 N·m listed)
MotorsTwo 3,000 WOne 800 W transaxle750 W std / 1950 W upgrade600 W hub motors (their spec)
Battery24V 50Ah LiFePO448V 30Ah LiFePO424V 22Ah AGM stdA24 power-bank pack
Claimed rangeUp to 30 mi (logged)~25 mi~4 mi std2 hours
Cart weight160 lb129 lb~110–155 lb53 lb
Load400 lb demonstrated350 lb rated300–500 lb (their FAQ)220 lb moving / 440 static
Tires16.5" PU balloon11.8" Wheeleez12" std / 16.5" upgrade10" balloon

Explore the cart in 3D — orbit the frame, steering, and drivetrain. Open the 3D model →

Available now · $79

Build one yourself

I built the cart, then wrote down exactly what I did. Cut sheet measured off the real frame. Every update is free on the same download.

  See what’s inside →

Also from this shop
The Jobsite Runner — remote-control jobsite utility cart, concept drawing

The Jobsite Runner

A remote-control jobsite cart concept in development, based on the beach-cart platform. Planned with flat-free tires, a flat deck and a handheld transmitter. Price, specifications and availability are to be confirmed.

The Jobsite Runner page →

FAQ
Is this the e-Beach Wagon?

No. The autonomous follow-me beach cart in the viral TikTok videos is a one-of-a-kind machine designed and hand-built by KMJ Dynamics. It drives itself — a wearable UWB tag and four corner receivers track the operator so the cart follows hands-free, while 360° lidar steers it around obstacles. e-Beach Wagon is an unrelated company whose electric wagons are hand-throttle driven: the operator steers and controls speed with a thumb throttle, and as of August 2026 they do not offer a self-driving or follow-me product. If a search result pointed you to a store-bought electric wagon, that is not the cart from the video.

Where can I buy one?

The self-driving cart is not for sale — there is one, in the shop. The remote-control version is in its first production run. New deposits are paused while pricing is updated. Join the list and you will hear first. Or build your own.

How much does the RC cart cost?

Pricing for the RC cart is being updated, and new deposits are paused until the new price is posted. Welded aluminum frame, two 3,000 W motors, a 1.3 kWh LiFePO4 battery, industrial 24V steering servo, 16.5-inch balloon tires. Join the list and you will hear the new price first.

Who built it?

I did — the welded aluminum frame, the carbon-fiber-nylon printed hubs, and every line of the autonomy software came off the same bench at KMJ Dynamics. The whole build is documented publicly with dated videos: early follow-me tests in July 2026, and the viral video that passed a million views in August 2026. The RC carts are the first production run.

How does it follow you — no camera, no phone?

A small ultra-wideband radio tag on your wrist gets ranged by four receivers on the cart's corners, which pins your position many times a second — no camera, no phone, no GPS. The cart steers to keep tracking behind you, with obstacle sensing from a 360° lidar and a six-sensor TFmini ring. Prefer to drive? A switch on the remote hands over full manual control any time.

How far does it go on a charge?

Up to 30 miles per charge — from logged current-per-mile data on the cart, not a brochure estimate.

Can you drive it with the remote?

Yes. Electric wagons you can buy today keep the operator on a handle. This cart is driven from a handheld transmitter — servo steering, dual motors, you stand apart from it. That same architecture is what lets the follow-me brain drive it.

What is the Jobsite Runner?

The Jobsite Runner is a remote-control jobsite cart concept in development. Price, final specifications and availability are to be confirmed. No deposit is required. Waitlist: email hello@kmjdynamics.com with subject “Jobsite Cart Waitlist”, or see the Jobsite Runner page.