![[Ben] at workbench with 3D-printed sea scooter](https://hackaday.com/wp-content/uploads/2025/08/sea-scooter-1200.jpg?w=800)
To every gadget, tool, or toy, you can reasonably think: ‘Sure I could buy this… but can I make it myself?’ And that’s where [Ben] decided he could, and got to work. On a sea scooter, to be exact.
This sea scooter was to be a fully waterproof, hermetically sealed 3D-printed underwater personal propulsion device, with the extreme constraint that the entire hull and mechanical interfaces are printed in one go. No post-printing holes for shafts, connectors, or seals. It also meant [Ben] needed to embed all electronics, motor, magnetic gearbox, custom battery pack, wireless charging, and non-contact magnetic control system inside the print during the actual print process.
As [Ben] explains, both Bluetooth and WiFi ranges are laughable once underwater. He elegantly solves this with a reed-switch-based magnetic control system. The non-contact magnetic drive avoids shaft penetrations entirely. Power comes from a custom 8S LiFePO₄ pack, charged wirelessly through the hull. Lastly, everything’s wrapped in epoxy to make it as watertight as a real submarine.
The whole trick of ‘print-in-place’ is that [Ben] pauses the builder mid-print, and drops in each subsystem like a secret ingredient. Continuing, he tweaks the printer’s Z-offset, and onwards it goes. It’s tense, high-stakes work; a 14-hour print where one nozzle crash means binning hundreds of dollars’ worth of embedded components.
Still, [Ben] took the chance, and delivered a cool, fully packed and fully working sea scooter. Comment below to discuss the possibilities of building one yourself.
Someone needs to send this guy a book on “design for maintenance”.
Nobody is going to use it more than three times, doesn’t need to be maintained. It’s a youtube video
Good point. I didn’t actually watch the video. Who is today’s sponsor?
Incredibly, no one!
Incredibly, No One™.
Famous for their invisible products, made from unobtanium. a key player in the vaporware world.
“one nozzle crash means binning hundreds of dollars’ worth of embedded components.”
Indeed. Great design. I wonder why we’ve never seen this before.
Apple enters the chat
I heard you like spicy epoxy sauce on your laptop batteries
Only to help our wonderful users enrich their life and get into the exciting world of spending.
Samsung et al hurriedly joins the chat, as it they got there first…
Who’s watched the video of the guys burning piles of thousands of cell phones to get the gold out? Designed for maintenance and recycling indeed!
Very imaginative! That’s a great idea and well done. My concern is whether it’s actually waterproof. I 3d printed a siphon for an aquarium a few years ago, ~2 mm wall thickness. I was surprised to find that it was not gas tight. It would flow fine but in low flow states, air would seep in and the siphon would stop working. I ended up melting the outside surface with an iron to make it gas tight.
I wonder if the part about epoxy might already have addressed your qualm.
“one nozzle crash means binning hundreds of dollars’ worth of embedded components”
No it doesn’t – what a silly thing to claim – it would be easy to recover the internals from the shell and try again… it’s not being flooded with potting compound… nor is the shell bonded to it beyond a tiny bit of glue.
Not only that but there’s not even really a need to print it in one piece since you’re ultimately gluing and epoxying the shell later. As for maintenance (if there is any to perform) you can easily cut the shell, re-glue and apply some epoxy to the cut.
It’s a brilliant idea – it’s just a shame this prototype is lacking in real output power and the wireless charging is slow – could’ve embedded a couple of copper contacts in the shell and epoxied around or cleaned the epoxy from them and designed a magnetically attached charge connector to get many amps of charging.
Of course they would not have to “[bin] hundreds of dollars’ worth of embedded components,” but saying “we would just bust everything out and restart” is hardly working up any suspense/drama for the viewers, innit?!
What a fantastic project! Absolutely brilliant and such an ingenious approach.
This is a wonderful example of how a bunch of disparate technologies can be combined effectively. The whole series goes through each step really well. I especially like the way empirical tests are used to arrive at the most optimum outcome. Great project, and a lot to learn from!
The many “channel owner stupid faces” on YouTube thumbnail screens are amusing to me but, personally, they don’t make me any more likely to watch a video. I guess they must do so for others because so many use them.
‘Channel owner surprise butt sex faces’
like everyone else, i was uneasy when i read about using FDM plastic as a waterproof vessel. and when i saw epoxy to waterproof it, i was like, why are we suffering all of the indignities of single-piece printing if we accept that the 3d printed component isn’t actually waterproof? personally i’m a big believer in compressed rubber washers / gaskets, and off-the-shelf solutions (canning jars, pvc pipe, etc).
but i’ve done the pause and install trick myself. impressive to take it to such a ridiculous extreme. and i definitely love the obsession with avoiding penetrations!
What’s interesting is, when I was new to 3D printing and had never read that FDM prints aren’t watertight, I printed a small water tank out of PLA to feed a terrarium mister.
That was a couple years ago and I haven’t seen it leak yet…
As for the print in place stuff here, I had a similar thought. There are definitely easier ways to go about this design, BUT it’s pretty neat to see someone tackle the challenge and show the fixes, as they might be useful to know in the future for other things.
There are perhaps more serviceable, and powerful diy solutions it there, like: https://discuss.bluerobotics.com/t/introducing-the-diy-t500-dpv/18922
Hah – I played subnautica and using seaglide chronically filled me with the urge to build one myself, haha