Halloween is popular for a lot of reasons and it is safe to say that “creative expression” is near the top of the list. That extends beyond store-bought costumes and decorations to DIY projects. If you want an excuse to make something impractical, Halloween can provide that. And if you want that thing to move, an Arduino and Bottango software are there to help, as proven by this disturbing animatronic Halloween doll built by Cameron Coward.

Coward started with a creepy doll procured at a thrift store, putting its porcelain head, hands, and feet onto a 3D-printed skeleton. The skeleton’s arms and legs are four-bar linkages, which produce the unnerving motion that falls into the uncanny valley. In total, there are five servo motors: one for rotating the head and four for actuating the limbs. 

An Arduino UNO Rev3 board controls the servo motors through an Adafruit 16-channel PWM servo driver board. That Arduino acts as a hardware driver for Bottango, which is software that was developed specifically for animatronics projects like this one. 

Using Bottango, Coward was able to create complex animations that involve all of the servo motors moving simultaneously. A child-size onesie (another thrift store find) covers the skeleton and electronics, completing the illusion of a doll come to life.