In this project we had the task of making a functional prototype on a Halloween decoration using different arduino components such as LEDs, sensors, speakers, etc., our choice has been to develop a coffin where inside we find a skeleton that rises when it detects people

The operation of our prototype begins when the detector located at the bottom of the coffin detects something close, at this time the system activates a servomotor which causes a skeleton with a range of 90 degrees to be raised or hidden.

At this same time, the buzzer is activated by playing a song while the skeleton is rising.

Project by Marc Vila, Javi Abad and Pau Carcellé

Step 1: Materials and Components

Construction materials:

6x of wood with their respective dimensions

1x Plastic Skeleton

1x Spiderweb

12x Spider

4x Hinge

Black paint

Electronic materials:


Ultrasonic Proximity Sensor HC-SR04


Bakelite plate

Arduino UNO plate

Connection wire



Step 2: Design a Coffin

Drawings of outer design of the coffin were made by hand. With this fast sketch and 3d we organize ourselves to know the parts of the coffin and so we can assemble it.

Here below we enclose a 3d design that can help you make the coffin

Step 3: Cut and Assembly

With the measurements already defined, we go on to cut all the wooden parts and then join them with hot silicone.

First we create the structure of the coffin and then add the lower base and slit the same to make the lid of the coffin. This cover will be formed by two parts that will be subjected by 3 hinges.

Step 4: Paint the Coffin

Once we have the coffin mounted, we will proceed to give it a layer of black paint.

Step 5: Skeleton Mechanism

We use a wooden stick and some flanges to attach the skeleton to the servomotor to be able to perform the movement. Then we made two holes in the lower part of the coffin to be able to place the Ultrasonic Proximity Sensor.

Step 6: Electronic Connections

Step 7: The Code

When someone gets closer to the ultrasonic sensor, the melody of the buzzer begins to sound and the servo is activated changing its angle from 0 to 85 degrees. So, when the sensor detects no presence there is a delay of 0,5 seconds and then the melody stops and the servo goes back to the starting position.

Step 8: Total Assembly

With the code programmed correctly and the two parts of our prototype already assembled, (coffin and skeleton) we will proceed to connect the entire electrical scheme by joining the cables of the board to our components to later verify that everything works correctly.

Later we will make a decoration in our coffin with the fabric and different spiders.

Step 9: Try to Scare Someone

Finally it is time to check that the movement of the skeleton is correct.

After different tests, we have been able to define the angles perfectly so that the skeleton does not strike at the base of the coffin, firstly the angle of descent was too aggressive and make a very abrupt descending movement.

Below you can see the operation of the prototype with a video.

Step 10: Conclusion

Although the principal objective was design a Halloween decoration, we thought we had total liberty to create any prototype. In this way we could think different ideas with the team and finally combinate this ideas to create our final project.

We think that working with arduino will facilitate us a lot in the future to creating new projects. During these weeks we have learned and lost the fear of making different prototypes with electronics, which will give us better quality and finishes in the future projects.

Finally, we want to say that working in group has made it easier for us to carry out this project. Each person in the team has contributed with different skills and practically we haven’t had any problem.