Bring Your Pumpkin to Life with Mechanical Movements

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Bring Your Pumpkin to Life with Mechanical Movements


Carving pumpkins is fun, but after a while it can become routine. Cut the triangle eyes, a triangle nose, then a mouth with a tooth or two hanging out. Engineer Ben Brandt, however, decided to take things one step further, and construct his pumpkin so that the eyes and tongue move via a crank-driven cam mechanism.

Per his Instructable, “The source of the motion in this mechanism is a simple offset/eccentric cam… basically a circle rotating off-center.” This “circle-cam” is made by attaching several washers together, which are then attached inside the pumpkin. The eyes are connected to one piece of metal made out of aluminum flashing, which is pushed left and right by the washer. The tongue is attached in a similar manner to the eyes, but in a vertical orientation (and with the addition of a fishing line).


One thing that I thought was especially interesting, as it could be applied to many different kinds of “vegetable hacks” was his pumpkin attachment method. Brandt pre-drilled holes, and used an anchor fastener meant for mounting things to sheet rock. According to him, “I was really impressed with how tightly it held. This turned out to be a great fastening method with soft materials.”


Although not really obvious from the video below (though quite evident in the above picture), this pumpkin is hand-cranked. According to Brandt, “You could connect a motor to the back, or maybe you have friends or guests that would like to turn it themselves.” With a motor attached, one could potentially hook up a passive infrared sensor and even lights to react to trick-or-treaters automatically. Still, there is something quite satisfying about a purely mechanical movement.

YouTube player

If you’re curious as to how Brandt came up with “Marty the Mechanical Moving Pumpkin,” the story is quite simple. He wanted to use the phrase “mechanical moving,” and though a bit more alliteration was in order. It is a little hard to forget the “M” sound repetition, so it’s something to think about when uploading your own videos!

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Jeremy is an engineer with 10 years experience at his full-time profession, and has a BSME from Clemson University. Outside of work he’s an avid maker and experimenter, building anything that comes into his mind!

View more articles by Jeremy S Cook


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