Claude runs robot arm to paint watercolor tree overnight
A Berlin engineer's video shows the AI mixing red, sienna and madder after its palette ran short, then finishing a painting in 303 brushstrokes.
Design engineer nil, who is based in Berlin, posted a video on X on November 6 showing Anthropic's Claude controlling a robotic arm to paint an autumn tree in watercolor overnight, according to aitimes.com. The run included the model mixing its own paints when the colors it needed ran out.
At around 4am, Claude found that the shades it needed were missing from its palette and mixed red, sienna and madder step by step on a second palette. It photographed each palette well to check the colors and then continued painting without further human instruction.
The painting took 4 hours 30 minutes and 303 brushstrokes. Claude Opus 5.5 was called 181 times over the session, at a list API cost of 18 dollars.
The setup used UFACTORY's 7-axis xArm 7 robotic arm and was built on nil's robotic painting project PB27. nil has been developing PB27 since June 2026, and the control software was written with AI coding agents including OpenAI Codex and Anthropic's Claude Code.
The video passed 1.2 million views on X. nil said he is considering a “robot art club” that would ship original AI-made paintings to members.
Quick answers
Which robotic arm did Claude use to paint?
The setup used UFACTORY's 7-axis xArm 7 robotic arm, built on nil's PB27 project.
How much did the painting session cost?
Claude Opus 5.5 was called 181 times, at a list API cost of 18 dollars, and the painting took 4 hours 30 minutes and 303 brushstrokes.