Side quest · On the workbench

I’m teaching a water dish to count.

Fenrir is a dog bowl I’m building on my workbench. It knows which dog is drinking and how much, and over time it learns what a normal day looks like for each of them.

Why build it What’s on the bench

Why build it

Plenty of homes have more than one dog and one water bowl. The bowl gets refilled all day, and nobody has any idea who’s drinking what.

That matters more than it sounds. A dog suddenly drinking a lot more, or a lot less, can be an early sign that something’s off, and it’s the kind of change nobody notices until it’s a big one. So I wondered: could the bowl notice for me?

It turns out the answer involves a scale, a tag on each collar, a lot of 3D printing and more soldering than I’d planned on. Which is the fun part.

What it does (when it works)

Spots who’s at the bowl. Each dog wears a little tag on its collar, so every drink gets put down to the right dog.

Weighs every drink. The bowl sits on a scale, so it knows how much went down.

Learns each dog’s normal. After a while it has a feel for a usual day, and can speak up when one dog is way off it. Hot days get a pass.

Nags me to refill it. Before the bowl runs dry, not after.

It won’t diagnose anything. It just notices when something has changed, so I know to pay attention.

What’s on the bench

Most of what I build lives on a screen. This one has a soldering iron, a pile of printed parts and some very patient test dogs in it.

3D model of the dish: a round, ribbed housing with a steel bowl dropped into the top — **The 3D model.** The housing as designed, with the bowl dropped in. The real one is coming off the printer a piece at a time.

The print A custom 3D-printed housing, designed in code rather than drawn, so when the bowl turned out bigger than its listing said, every part grew to fit.

The electronics A tiny Wi-Fi board, a scale and a tag reader, wired up a piece at a time, with a few “why is it reading 40 kg?” moments along the way.

The software Code on the dish, somewhere online to keep the history, and an app to see it all, written with Claude Code and tracked in Kantan.

The logo A happy dog with a drop of water falling from its chin. Every project deserves a mascot.

In use

The dish has a website and an Android app to go with it. Both are early, and the drinks here are sample data.

The Fenrir website dashboard: a card for each of two dogs with today’s total, progress toward a usual day and the last two weeks of bars, the dishes and their status, and a table of recent drinks — **The dashboard.** Each dog’s total for today, how it compares with a usual day, the last two weeks at a glance, and every drink as it comes in.

One dog’s page on the website: today’s total, 7- and 30-day averages, intake per pound of body weight, and a 30-day bar chart with a shaded usual range and four days in amber — **One dog’s month.** Thirty days of drinking against that dog’s usual range. The amber days are the ones that stood out.

The Android app’s Today screen: a card for each dog with today’s total and a two-week bar chart — **The Android app.** Today, for every dog in the house.

The Android app’s Pets screen listing two dogs with their breed, weight and age — **Pets.** Each one with a profile and a collar tag.

Editing a dog in the Android app: photo, name, dog or cat, breed, weight and birth year — **A pet’s profile.** A photo, a breed and a rough weight are all it needs.

The Android app’s Add a dish screen: scan the code on the dish, or type it instead — **Adding a dish.** Scan the code on the dish and the phone does the rest.

Where it’s at

Very much a work in progress. Parts are printing, wires are getting soldered, and the first real test is a full bowl and some thirsty dogs. If it works, I’ll build a few more. “Fenrir”, the giant wolf of Norse myth, is just the codename.

Done The idea and a logo Priorities.

In progress A working prototype Printed, wired and weighing real water.

In progress The app A website and an Android app, to see who drank what.

Next The dog test Real dogs, one bowl, a few weeks of real life.

Built something like this?

Or have a dog with opinions about water bowls? I’d love to hear about it.

Say hello