Sensing spider prank (3D print Edition)

In this project, you will learn multiple aspects of Arduino while building an automated sensing spider.

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Halloween is coming and spiders are perfect for creating a good scare. This project can be either 3D printed or made from wood. A great and challenging introduction to Arduino that demonstrates a practical use of multiple inputs and outputs.

Using a PIR sensor our target is automatically detected and our spider deployed rapidly for the perfect fright.

Check the video links if you get stuck on a step these are timestamped so should go directly to the place you are at.

The project uses an Arduino UNO to sense our victim with a PIR sensor. Once they have been detected a small DC motor with a spool of cotton unwinds to deploy our spider. A microswitch keeps a check on our spider to make sure it doesn't get too carried away. 

The project has STLs if you have access to a 3D printer or templates for cutting out on wood or a laser template for laser cutting. 

If you are new to Arduino this is the perfect project to build something and see a practical outcome. 

All the code is included and the parts should be readily available throughout the world. 

See it in action below.

Standard Tesselated Geometry - 4.42 MB - 10/12/2022 at 23:43


Standard Tesselated Geometry - 41.39 kB - 10/12/2022 at 22:00


Standard Tesselated Geometry - 110.92 kB - 10/12/2022 at 22:00


Standard Tesselated Geometry - 38.17 kB - 10/12/2022 at 22:00


Standard Tesselated Geometry - 289.24 kB - 10/12/2022 at 22:00


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  • 1
    Print STLS.

    Print the STLS included in this build. There should be no support required for the main chassis, the spool will require support. Use tree supports if your slicer has this option The only change I recommend is having 100% infill around screw holes to prevent splitting of the PLA. The spider should be printed with 20% infill and upside down on an FDM printer.

    Main chassis

    Limit switch paddle

    Drive boss


    PIR sensor holder

  • 2
    Install Arduino

    Screw the Arduino UNO into place using 4 6x3 screws.  More details in the video here

  • 3
    Motor installation

    Using a small hammer tap the drive boss onto the shaft of the motor. More details on the video here

    Slide the motor into the base of the chassis.

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