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. I hand-build them.

$5,000, delivery included from Maine to New Jersey — inside that range I deliver every cart myself. Outside it, the cart ships freight with the first $250 credited, and the battery ships to you direct from the manufacturer. The $500 deposit holds a numbered build slot and is fully refundable until you approve your final invoice. If deposits ever outrun the current batch, your call: a full refund, or first in line for the next one.

160 lb
Total weight
400 lb
Payload
4.5 mph
Top speed
10:1
Drive · inclines

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 with five roof-shingle bundles that weigh 80 lb each.
Speed~4.5 mph. Reverse about half that.
DriveTwo 3,000 W motors, one per rear wheel. #40 chain, 10:1 two-stage jackshaft — designed to climb steep inclines.
SteeringTwo kingpin pivot points on a fixed U-shaped steel support. 24V industrial servo. No front axle.
Wheels16.5" PU balloon tires on two-piece printed hubs, tire bonded. 2–4 psi; 2.5 psi for soft sand.
Battery24V 50Ah LiFePO4, under the frame.
ControlHandheld RC transmitter. No Pi. No follow-me. No lidar.

Next to the others

Their published numbers. Ours from the spec above. Range for this RC cart is not listed — it hasn’t been measured without the follow-me computer running.

KMJ RCe-Beach WagonSandhopperLitefar B1 new 8/18
DriveRemote. No handle.Handle + thumb throttleHandle + throttleHandle. Optional remote.
Gearing10:1 jackshaftTransaxle (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 range—~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

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, while a 360° scanner steers it around people and stops it at curbs.

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

A 360° scanner steers it around people and stops it at curbs and drop-offs.

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.

Printed hub face
Finished wheel with new hub

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 →

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

Remote-control jobsite utility cart. Same welded frame as the beach cart — flat-free tires, flat deck, you drive it from the transmitter. No follow-me on this line.

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 open for deposits: $5,000, delivery included from Maine to New Jersey, and a $500 fully refundable deposit holds a numbered build slot. Reserve a build slot. Or build your own.

How much does the RC cart cost?

The RC cart is $5,000, delivery included from Maine to New Jersey. Welded aluminum frame, two 3,000 W motors, a 1.3 kWh LiFePO4 battery, industrial 24V steering servo, 16.5-inch balloon tires. A $500 deposit holds a numbered build slot and is fully refundable until you approve your final invoice — reserve yours here.

Who built it?

I did — KMJ Dynamics is a one-person shop. The welded aluminum frame, the 24V power electronics, the carbon-fiber-nylon printed hubs, and every line of the autonomy software came off the same bench. 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.

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, while a spinning 360° lidar watches for people and obstacles and stops it at curbs and drop-offs. Prefer to drive? A switch on the remote hands over full manual control any time.

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 the remote-control jobsite utility cart — same welded aluminum machine as the beach cart, trimmed for construction: flat-free tires, flat deck, driven from a transmitter. It does not include the autonomous follow-me system. Waitlist: email hello@kmjdynamics.com with subject “Jobsite Cart Waitlist”, or see the Jobsite Runner page.