Spooky skeleton and petrified pumpkin robots

This Pico-powered 3D-printed spooky skeleton and petrified pumpkin track your movements and know exactly when to (servo) motor into action. But Kevin has coded them to prove that they’re more scared of you than you are of them. They’re friendly Halloween tropes.

Kevin McAleer is our kind of holiday decorator. No shop-bought tat for this maker, oh no. He has, of course, decided to over-engineer the process of getting his house Halloween-ready by building his own decorations. And he’s gone one step further by making them smart enough to know when guests are leaning in to take a closer look, so they know when to start their performance.

kevin mcaleer spooky skeleton petrified pumpkin
If I were into sub-par puns, I would call these two best ghoulfriends

How does it work?

An ultrasonic range-finder detects when people move in front of it. Then the servo moves a mechanism that raises the eyebrow pieces and lowers the jaw piece, giving the robot its scared stiff expression. See — told they’re more terrified of you than you are of them.

Raspberry Pi Pico is the sinister force behind these spooky smart Halloween robots.

The build process

Parts list

An ultrasonic range finder doesn’t exactly “see” objects in front of it; it emits a high-frequency sound wave that bounces off nearby surfaces and returns to the sensor. But luckily it looks just like a pair of eyes, so, two birds and all that.

This project featured as one of Kevin’s live-streamed builds on his YouTube channel

No soldering required. All the parts fit together nicely. And the code is simple bare-bones (LOL) stuff. Easy peasy.

Everything you need to make your own petrified pumpkin or spooky skeleton is available to download or clone on Kevin’s GitHub.

Wiring diagram showing Raspberry Pi Pico connected to the servo and range finder
Simple, effective electronics – the Pico speaks to the servo and range finder, all tucked behind the 3D-printed face


Kevin has submitted the Petrified Pumpkin for this year’s #HackAPumpkin challenge. Now in its sixth year, it’s run by @RobotMakerGirl (Allie Weber) and Digikey. Submit your hacked hardware and join in the Halloween fun on Twitter.


Ben avatar

These look ace. Could I use Pico W to make remote controlled versions?

Toby avatar

Nice work Kevin. Might have to borrow (steal) that idea for some other projects!

Comments are closed