For his latest project, Will Cogley has created an animatronic heart so realistic that you might wonder if it’s the actual thing. 

The device is made out of molded silicone with fake blood poured on top to enhance the effect, and inside a trio of servo motors push the lower and upper sections of the prop out in a very lifelike pattern. 

Control is via an Arduino Micro along with an I2C servo controller, while power is provided by an external tether. A potentiometer on the back is used to vary heartbeat speed. 

He also made a simpler — and less potentially terrifying — version with a cloth exterior. This one is battery-operated and runs on a motor and linkage system, perhaps making it good for a nice portable joke!

Cogley has uploaded a new video that walks you through the build process as well as a written tutorial.