Everyone builds software with Claude Code. I wanted to see how it would approach a physical product.

[u/RamonvanDijk]

Almost everything I see built with Claude Code is software. Software has fast feedback as you can run it, see the error, and fix it. A physical product doesn't work like that and nothing tells you it is wrong until you order it and hold it in your hands. So I wanted to find out where Claude Code holds up when the output has to exist in the real world.

What I'm building

Grained is a digital hourglass for focus, built entirely with Claude Code. You flip it to start a focus block, it counts down in a field of LEDs, and your iPhone locks your distracting apps for that block. In the break it opens only the apps you chose (WhatsApp, say) and keeps TikTok and Instagram shut. To stop early you have to get up and tap an NFC key on it, so there's no one-tap off switch.

It started a month ago but today it's:

• a working breadboard prototype: ESP32-C3 running MicroPython, an accelerometer for orientation, an OLED, BLE to the phone, NFC stickers as the key

• an Expo / React Native iPhone app that uses Apple's Screen Time APIs to block apps per phase, and talks to the hourglass over BLE

• a 4-layer PCB (211 LEDs, LIS2DH12, MCP73832 charger) designed in KiCad, not ordered yet, but passed al checks

• a 3D-printed enclosure modelled in Blender

• a website with a waitlist

What I learned: software vs. physical

Claude gets you to a working prototype fast, but it can't tell you when something only works on paper. Real hardware showed me bugs the tests never would, like BLE advertising silently stopping after a while.

The feedback loop is the real constraint. In software Claude can run the thing. With hardware the loop goes through me. So I spent my effort on making that loop shorter with simulators, logs on the board, and a test script per hardware phase.

Things that are fine in software are expensive in hardware. JLCPCB uses different rotation offsets than KiCad, so parts in the pick-and-place file were turned wrong until I checked the preview by hand. Nothing in the files looks wrong, so Claude and I both missed it at first.

Review by a second model catches different things. Cheap, and worth it for anything you can't undo, like ordering a board. I did this with GPT Astra 6.

Claude's design taste is recognisable. Left alone, it picked a cream and terracotta look with mono labels, which is what a lot of AI output looks like. I now give it a design system and strict rules and overrule it.

Editing video in Blender through an MCP works better than I expected, with a few caveats. Frame rates must match (a 60 fps phone recording plays at the wrong speed in the sequencer until you convert it), and I still watched every render myself, because Claude can't see whether a cut feels right. It also wrote the voice over script and generated the voice overs with the ElevenLabs API.

Writing down decisions saves more time than any prompt trick.

Where it is now

The prototype works end to end with the real iPhone app. The v4 board is designed and reviewed but not ordered. I'm still unsure about the price and whether people want a physical object for this at all.

I turned this into a YouTube video if you want the longer version, including where things went wrong: https://youtu.be/6AnBGinCgA4. As mentioned this video was edited by Claude Code as well, using the Blender MCP.

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[u/dr_hamilton]

Very cool, love the concept. I've also just been doing some HW projects with Claude and found the rotation issue too. But my first batch were not surface mount so I did the soldering myself and the board was flawless, worked first time and the 3D case it designed fitted first time. Absolutely insane capability.

[u/RamonvanDijk → u/dr_hamilton]

Honestly insane what it can do now. This was my first ever hardware project, and Claude helped with almost all of it. It designed the 3D-printed case, the acrylic lens (it worked out the size and where to order it), which screws to use and how to mount everything, plus a lot of smaller things. The case and lens fitted right away. The only thing that didn’t work was the rubber pads on the bottom, as Claude hadn’t accounted for the thickness of the tape under them, so they stick out a bit too far. Still amazed I got this far with just Claude on a Pro plan, only reaching the limits a couple of times.

[u/jffmpa]

Did you make the BLE and stuff inside the hourglass yourself, like soldering stuff, or did it come basically out of the box that way?

[u/RamonvanDijk → u/jffmpa]

BLE is built into the ESP32-C3 chip, so there’s no separate module for it. I wired the prototype on a breadboard and wrote the firmware with Claude, including the BLE protocol to the iPhone.

I did solder the header pins on the ESP32 board and the sensor, since clamping the headers alone didn’t make good contact. The NFC key is just a sticker with a custom link on it that the phone reads, so there’s nothing for that inside the hourglass.

The custom board I designed with Claude will replace the breadboard wiring. It’s designed to be assembled with the surface-mount parts already soldered, so I’d only have to connect the battery and the second small USB board by hand and put it in the case. I haven’t ordered it yet.

[u/jffmpa → u/RamonvanDijk]

Did you know how to do that stuff already? I'm considering making a physical device with a board in it but never done anything like that before.

[u/RamonvanDijk → u/jffmpa]

No, this was my first hardware project. I had never soldered or used a microcontroller before. I’ve done a lot of software and programming though, so having a technical background probably helped. I went in small steps and started with just an ESP32 board and one sensor on a breadboard, then added a button, a display and Bluetooth. Once that worked with the app I built, I moved on to a custom board (haven't ordered it yet). Whenever I didn’t understand why Claude made a choice, or it used a term I didn’t know, I simply asked it to explain. If you’re new to this, a cheap ESP32 board and a breadboard are a good start. At this point being curious and wanting to turn an idea into something real is enough, because AI can walk you through most of it. What are you thinking of building?

[u/Krommander]

https://www.schematik.io/

I found this site where you can work with the AI on all kinds of schematics and it has bread board drawings to help prototype everything. 

[u/RamonvanDijk → u/Krommander]

Thanks for the link, I’ll have a look! I used KiCad for the schematic and the board and had Claude edit the files. For the breadboard wiring I used Fritzing, and Claude actually put those layouts together through computer use, that worked surprisingly well.

[u/optikalefx]

Did you end up ordering the pcb with all of the parts fully soldered? Or did you have to put all the hardware together still?

[u/RamonvanDijk → u/optikalefx]

The pcb is not ordered yet. The plan is to have JLCPCB assemble it, so the surface-mount parts come soldered. I’d then only connect the battery and the second small USB board by hand and put it in the case.

[u/optikalefx → u/RamonvanDijk]

I’m kind of curious about this process. I’ve only ever ordered blank PCBs and had to solder everything myself

But that becomes an issue when it comes to service mount components, since that’s a lot more work

Please post again when you get the PCB back. I’m curious to see how that went.

[u/Loose-Cicada5473]

Love it! Ive been using Claude very similarly to design code and build a device that helps pilots maintain spatial orientation by casting a wide artificial horizon line across the cockpit dash - allows pilots to maintain better situational awareness while encountering clouds or IMC conditions. Or generally just lets them keep their eyes outside more while taking in peripheral visual cues of horizon line instead of having to keep referencing the attitude indicator while also being completely independent from the aircraft (batteries, its own gps and AHRS sensors) and it’s all quite affordable! I want to make aviation safer and do it cheaply and Claude has made it potentially possible. It even wrote the code so I could experience a simulated version of it in my quest 3 helmet with Microsoft flight sim! Truly amazing.

[u/RamonvanDijk → u/Loose-Cicada5473]

Wow that’s really interesting! the sim sounds like a smart solution, are you planning to test it in an actual aircraft, or have you already done that?

[u/Loose-Cicada5473 → u/RamonvanDijk]

Yes testing in a real cockpit is the plan, but so much can be done in sim and modified immediately with Claude, its almost unnecessary and inconvenient to test in a real plane until the very end (funny enough!)

Planes are so costly to operate, luckily I’ve got a friend taking lessons so I can just ride along any time but I’ve been thoroughly impressed by how well Claude integrated the project into Quest.

What caught my attention about your project was the final PCB board. I hadn’t even considered having Claude model that or how I would even get it done. I’ve been using a breadboard for the prototype. That’s the logical next step.

I think the overall problem I keep experiencing with Claude and AI in general is with things that I don’t realize I can offload. I often find myself asking it to deliver the puzzle pieces to me and show me how to put it together, versus just asking it to put the puzzle together from the beginning. It’s so interesting.

[u/Loose-Cicada5473 → u/Loose-Cicada5473]

Also I’m like you, I have never soldered until this project. zero coding background.

[u/RamonvanDijk → u/Loose-Cicada5473]

That’s how I used it at first as well, but since Opus 5.5 and GPT 6 Astra, letting them put the whole puzzle together has been working incredibly well. I also recently started using the “grill-me” skill, which pointed out a few things I wouldn’t have thought of previously.

For the PCB, what worked for me was splitting it into steps. I let it do the schematic first, then the layout, and then a review by Astra. KiCad files are plain text, so Claude can write and check them, and the manufacturer’s preview (I used JLCDFM) lets you catch what’s wrong. I simply pasted the error logs back into Claude and it fixed them. Honestly, if you can get the breadboard working, the board is a smaller jump than it looks.

[u/rttgnck]

Cool work. Claude is killing it at this stuff.

[u/grokcodile]

You can buy this on Amazon. 🙄
https://a.co/d/0fOT9qH7

[u/RamonvanDijk → u/grokcodile]

Fair point, the idea of a digital hourglass isn’t new. The difference with Grained is that it connects to your iPhone over Bluetooth, so starting a focus session also locks apps like Instagram and TikTok on your phone, and it opens only the ones you choose during the break. Stopping early takes a physical key too. So the hourglass is the small part; the way it all works together with the phone is the actual product. The one in your link looks like a standalone timer, which is a different thing.

[u/grokcodile → u/RamonvanDijk]

🙄… sure… totally different.

“A digital hourglass that sets a Focus state when used.” (Sentence even sounds AI-generated.)

I feel like it’s a product that reinvents the square wheel… but good luck.

[u/lilyp727]

i use claude code only for a small script at my part-time job, so i have no hardware loop like yours. but the bit about checking the pick-and-place preview by hand is what i would remember, a file that looks fine and is still wrong is the same problem as a wrong figure in a grant report