Anthropic says Claude Fable 5.2 designed three gadgets that worked, from circuit board to firmware
Diode's engineers built them with no circuit fixes. They are untested prototypes, and Anthropic has a commercial tie to Diode.
On 9 November 2026 Anthropic reported that Claude Fable 5.2 had designed three electronic devices from short prompts: a USB speakerphone, a voice-assistant hub and a handheld virtual pet. For each, Claude wrote the specification, drew the schematic, placed the parts on the circuit board and routed the copper tracks between them. It also designed a 3D-printable case, wrote the firmware (the code that runs on the device) and listed the parts to buy.
Engineers at Diode Computers, a circuit-board company, built the boards under Claude’s direction. Anthropic says the prototypes worked without fixes to their circuitry, and that the speakerphone still works after weeks of use. About a year earlier, the models it tested could not reliably lay out a board. Diode’s engineers had many boards from those models that were 95% complete but unusable.
Diode ran its own board-layout test, PCB Gym, where a model must place parts and reroute tracks on boards whose layouts were removed. Fable 5.2 scored 69% and Fable 5 scored 25%. On the public BenchCAD 2.1 test, which asks models to rebuild 3D parts and boards from drawings, Fable 5.2 scored 83.5%. The BenchCAD leaderboard lists Fable 5.1 at 44.4%, so the gain is about 1.9×.
Claude also reworked its own designs without being told to. In one case it deleted and rerouted the hub’s tracks dozens of times. In another it wrote its own routing program (a tool that draws the tracks) in about half an hour.
What it means
Anthropic reports that the model can now carry a small hardware design from prompt to a working board, a step that earlier models failed at. The work still needed human engineers to build and test the devices, and nobody has shown that the designs would pass the checks needed to sell them.
Caveats
- This is Anthropic’s account of work done with a company it has a commercial relationship with, which the post states. No outside engineer has reviewed the designs.
- PCB Gym is Diode’s internal benchmark. We found no public copy, so its 69% and 25% cannot be checked.
- The leaderboard marks the 0.835 as read from Fable 5.2’s system card chart, not run by BenchCAD. The top setting costs about $50.90 per case, against about $1.89 at the lowest. The Fable 5.1 figure is BenchCAD’s own run.
- The devices have had no electrical validation, antenna tuning, thermal testing or certification, and were not designed for mass production.
- Claude was not connected to test equipment or factory machines. Diode’s engineers built and tested everything by hand, and gave short prompts such as “clean up the schematic” and “continue”. Anthropic names no designs where Claude failed.