The Booth Cannons
A group of 5 cannons which smoked and lit-up as a light feature for the 2026 Fringe Booth
Background and Concept
As part of the judging for Booth at CMU’s carnival, night time light displays tend to be high value items. Given that our theme for the year was Sea Shanties, and we were building a pirate ship, light cannons were a perfect fit.
Early on, we decided to synchronize them. Initially, we wanted sound effects, but that was too complex to justify. We also decided that a smoke effect would look nice, and at least improve the visibility of the light. The cannons were mounted to roof and angled out to be as visible as possible. We planned to 3D print the cannon bodies, and wire them with Arduino.
Design and Execution
The design process was fairly straightforward. We decided to use PVC pipe as the barrel to reduce the 3D printing time and material used. The back half of the cannon was a 3D printed sphere with a mount for the light and a hollow cavity for the electronics. The front half had a 3D printed ring to improve ascetics. The cannons were mounted to the booth with a simple bracket that was glued to the main body.
The cannons were each controlled with their own Arduino. This used a pair of relays to control the light and an ultrasonic humidifier for the smoke effect. The Arduinos were connected using barrel jack connectors to share power along the line, as well as to communicate with one another. While we considered a variety of communication methods, we chose UART for its simplicity. The arduinos were daisy chained together and would pass an array down the line. They would remove the first number from it to set their own delay and pass the rest on.
Ultimately we never used the smoke effect as the humidifiers were too uncooperative and required too much extra time to manage, especially as we neared the end of carnival. Otherwise, these cannons were effective and boosted our night time judging scores.