When Katie Dumont of element14 Presents received her Arduino UNO Mini Limited Edition, she was concerned that it would end up like most of her other pieces of hardware — either stored somewhere safely in its box or on a shelf for display. But because she wanted it to avoid this fate, her other idea was to feature it prominently within an amusing wearable.

For her project, a series of LEDs would be the main output as their color and animation can be changed dynamically. In addition to the lights, the necklace was planned to include its own LiPo battery pack for maximum mobility, although it would not feature any user inputs so that space could be saved. Each of these components were carefully laid out in FreeCAD and had a case constructed around them, which exposes the side of the pendant so that the LEDs can emit a faint glow onto the shirt material below, whereas the UNO Mini is front and center.

The device’s code is based on the preexisting Adafruit NeoPixel example, as it contains the typical rainbow and solid color modes. Because the top pins of the Uno Mini are exposed, connecting one of three digital inputs pins to ground will make the board enter a specific color pattern, otherwise it shows a default rainbow one.

To see more about how Dumont built this fun pendant, be sure to watch her e14 Presents video!