Claude designed three working gadgets, and Diode’s boards needed no circuit fixes

Anthropic says its Claude Fable 5.2 model designed three electronic devices with minimal prompting, and that engineers at Diode Computers built prototypes that worked without any fixes to their circuitry. The devices are a speakerphone, a voice-assistant hub and a handheld virtual pet.

Three devices from short prompts

Anthropic gave Claude a short brief for each product. The speakerphone prompt asked for a puck that plugs into a computer over USB-C, with microphones, a speaker, and Bluetooth through a PCB antenna. From there, Anthropic says, Claude wrote the specifications, drew the schematics, placed the components, routed the copper connections, designed a 3D-printable enclosure, wrote the firmware and prepared a parts list.

Diode, a company that designs and manufactures circuit boards, assembled the boards and ran the firmware under Claude’s direction. Anthropic says all three boards were manufactured directly from Claude’s design files, with no back-and-forth over adjustments, which the Diode team told Anthropic surprised them. The speakerphone has kept working for weeks, and the hub and the pet are also still in good order. Anthropic discloses a commercial relationship with Diode and says the two have worked together on PCB design since 2025.

Prompting was minimal, according to Anthropic: short directives such as “clean up the schematic” and “continue”, plus one question about whether the pet would work without a battery. Claude answered from the charger’s datasheet that it would run on USB power but that the charging light would flicker.

Benchmarks and a router Claude wrote itself

The biggest gain, Anthropic says, is geometric reasoning. On Diode’s internal PCB Gym benchmark, which removes the layout from a board and asks the model to place and route it, Fable 5.2 scored 69%, against 25% for Fable 5. On the public BenchCAD 2.1, which tests rebuilding 3D parts and circuit boards from drawings, it scored 83.5%, nearly double Claude Fable 5.1.

The examples are concrete. On the hub, Claude routed the USB and Ethernet pairs first, matched their lengths and added tuning zigzags. When KiCad’s one-track-at-a-time router proved too slow for a 100-pin connector, Claude wrote its own grid-search router in about half an hour. Anthropic says it lays a long track in roughly a second. For the speakerphone, Claude found the board could not drop into the case because the mute switch hit the back wall, and worked out a tilt of about 25 degrees during assembly. It also calculated that a 25 mm microphone port would resonate near 3.4 kHz, and chose a wedge-shaped case that shortened the ports to about 10 mm.

Why rerouting is the hard part

Anthropic’s account of the older models explains why this matters technically. Earlier systems rarely backed out of a bad layout, and Diode saw many boards that were 95% complete yet unusable. Anthropic says Fable 5.2 instead abandoned dead ends: in the hub’s log it noted the connections were “getting too tangled to trace visually” and deleted and rerouted tracks dozens of times. Placement and routing are tightly coupled, so a poor early choice can make the last connections impossible. Recognizing that and starting again is a different skill from drawing tracks.

Outside work suggests the field is moving in the same direction, and that the details matter. OpenAI has described its GPT-6 Astra model designing a talking “Codex pet” device, with two team members working for under a week and a contract manufacturer building prototypes in under a month, according to R&D World. The same report quotes an OpenAI researcher saying it “took a few rounds with the factory”. Anthropic’s claim of zero circuit fixes and no manufacturing rounds is therefore a stronger one, and it comes from Anthropic and its commercial partner, not from an independent test. R&D World also cites a NextPCB test in which the open-source Freerouting tool did the core routing for Astra; Claude’s custom router is a different route to the same bottleneck.

Prototypes, not products

Anthropic is clear about the limits. The devices have not been through electrical validation, antenna tuning, thermal testing or certification, and were not designed for mass production. Claude was not connected to test equipment or to the machines that build boards, so Diode’s engineers built and tested everything by hand. Anthropic says it does not yet know how the prototypes will hold up with long use or whether they would pass commercial certification.

The page also does not say how Fable 5.2 can be accessed for this kind of work, whether Diode’s design software is available to customers, or what a run costs beyond the API-cost axis of the PCB Gym chart. PCB Gym is an internal benchmark run by Diode, and the results are Anthropic’s own. Anthropic’s stated next steps are denser, faster and more complex boards, checking them in simulation, and learning from measurements taken on finished devices.

The release comes as Anthropic is also drawing attention for its finances; our earlier report covers the start of its IPO marketing amid a market rout.