DIY eFoil Build – From a Block of Foam to a Flying Board

crivenco · July 22, 2026, 9:53am

Hi everyone!

After spending countless hours reading build logs here, I finally decided it’s time to share my own project.

This is my first DIY eFoil, and instead of buying a complete kit, I wanted to build as much as possible myself. The goal wasn’t just to save money—it was to understand every single part of the system and learn along the way.

This thread will document the entire build from start to finish.

So far I’ve already completed (or nearly completed) most of the major components, and I’ll be posting the whole journey with lots of photos and technical details.

Here’s what you can expect:

Choosing and buying all the components
Designing the board in CAD
CNC cutting the EPS foam core
Laminating multiple layers of fiberglass and carbon fiber
🪽 Designing and building my own front wing
Building a custom 15S16P battery pack (BEAST!)
Installing the BMS and waterproof electrical system
VESC configuration and tuning
Bench testing the motor and battery before the first ride
(Hopefully…) successful water testing

Project Specs

Board

Custom CNC-cut EPS core
Carbon fiber + fiberglass composite construction
Approx. 168 cm × 60 cm
Custom designed from scratch

Battery

15S16P
LG M50LT 21700 cells
Around 80 Ah capacity
JK Smart BMS with active balancing

Electronics

Flipsky FSESC 75200 Pro V2
Flipsky VX3 Pro remote
Flipsky 65161 120KV motor

Propulsion

Folding propeller
Custom waterproof wiring and connectors

One thing I wanted from the beginning was reliability.

I know many DIY projects focus on making the lightest or cheapest possible board, but my priority has always been building something robust that I can trust on the water.

That meant spending a lot of time thinking about waterproofing, battery safety, connector reliability, cooling, and serviceability—not just performance.

I’m sure I’ve made mistakes already (and probably many more are coming ), so I really appreciate any suggestions, criticism, or ideas from experienced builders.

I’ll keep updating this thread as I organize the photos from each stage of the build.

Next posts will cover:

CAD design
CNC machining
Lamination process
Wing manufacturing
Battery build
Electronics installation
VESC setup
Bench tests
First ride

Hopefully this build log will also help someone else who’s thinking about building their own eFoil.

Thanks for reading, and let’s see if this thing actually flies!

crivenco · July 22, 2026, 10:32am

Part 1 – CAD Design

Before cutting any foam, I spent quite a bit of time designing the board in CAD.

Since this is my first eFoil, I wasn’t trying to build the smallest or lightest board. My priorities were stability, enough internal space for the battery and electronics, and a design that I could actually manufacture myself.

Final dimensions:

1680 × 600 × 130 mm
~71.7 L volume

After a lot of small adjustments, I finally had a model I was happy with.

Next step: turning the CAD model into a real board on the CNC machine.
V1 that was ugly and I refused to build it almost from the start:

V2 my actual board design:

Battery, controller, motor, wing, stabilizer …

crivenco · July 22, 2026, 10:45am

Part 2 – CNC Cutting and 3D printing

Time to make some filament foam dust.

The board was cut from an EPS foam block on a CNC machine. Seeing the CAD model turn into a real board was definitely one of the most satisfying moments of the project.

The machining came out better than I expected, with only a little hand finishing needed before lamination:

Wing, battery case and motor holder on 3D printer:

HOF · July 22, 2026, 10:47am

Nice!

Noticed you have an absolutely huge battery, whats the thinking behind it? i have 1/3 of yours and im satisfied with almost 1h run time.

Foilguy · July 22, 2026, 11:11am

A few things since you asked😉

Why a folding prop?
Why that size of battery? - larger than most.
I would suggest a VX5 remote - a bit more expensive than VX3 but proven reliable.
You don’t list what foil setup you are using.

crivenco · July 22, 2026, 12:05pm

I made a first test, I tried to get up on this board for an hour, and I spent 15-20% of the battery

crivenco · July 22, 2026, 12:13pm

I bought few different props and I’ll test them all
I knew that my board will be heavy, and I have a lot of friends that want to use it when we will go somwhere to swim. And I decided to make a battery for all of us and that’s mean that everyone can take his time and enjoy the ride for >20-30min
I bought a kit where VX3 was already included 1 year ago, and VX5 appears just now. Be sure that on next season I’ll buy VX5

elnillo · July 22, 2026, 12:31pm

I would also advise to half the battery. 2x 15S8P instead of 1x 15S16P
Less weight on board → more sporty foiling.
If you build your smaller second board, you will have less space for the 15S16P.

crivenco · July 22, 2026, 12:38pm

Part 3 – Fiberglass & Carbon Fiber Lamination

After CNC machining and final shaping, it was time to turn the foam core into a real composite board.

I used a combination of 2x fiberglass and 1x carbon fiber layers to reinforce the structure.

The main goals were:

Keep the board strong and stiff
Protect the foam core
Create a durable surface for everyday use

The lamination process was probably one of the most important and challenging parts of the build. A lot of preparation, sanding, and patience went into getting everything right.

Still learning with composites, so this was a big step for me.

there you can see that I installed mast holder made of steel reinforced with carbon:

then the battery hole reinforced with carbon:

crivenco · July 22, 2026, 12:41pm

I think you are right, and I’ll made one smaller battery

crivenco · July 22, 2026, 12:48pm

Part 4 – Battery Pack & First Motor Test

The heart of the project — the battery.

I built a custom 15S16P battery pack using LG INR21700-M50LT cells.

Battery specs:

15S16P configuration
80 Ah capacity
~54V nominal voltage
JK Smart BMS with active balancing (JK-B2A20S20P-HC)
40A charging capability
22kg weight 22 KARL!((

For the ESC I chose:

Flipsky FSESC 75200 Pro V2

Motor:

Flipsky 65161 120KV

Before installing everything into the board, I wanted to make sure the battery, BMS, controller, and motor were working correctly.

First power-up test was successful — the motor started smoothly and the system responded as expected.

Next step: waterproofing, final assembly, and preparing for the first water test.

S_Roger · July 22, 2026, 2:18pm

Wow, nice work @crivenco! That board looks very nice and well done so far.

I do agree with other comments about the battery being big, over 4kwh is massive! I have the same LG cells is a 10S11P configuration. That is around 2kwh and less than half the number of cells you have. I already think that battery is too heavy and I cannot imagine trying to handle your battery.
It should be capable of flying, but the swing weight of the battery will affect the handling and the feel of the board on your feet. Turning may be difficult, if you lean to far it will tip right over if you don’t have sufficient speed/lift.

Windigo · July 22, 2026, 2:54pm

Very nice work! I agrree with others the battery unnecessarily big and heavy. I use a 10S 55 A/H and I have gotten 1.5 hours out of it but usually after an hour I have had enough. You battery could last like 3 hours but you will need superhuman strength for you legs to last that long efoiling.

ludwig_bre · July 22, 2026, 4:21pm

And superhuman strength carrying this big battery to the water

But it looks very nicely built!