Box Thing (NFC Audio Player)

Situation

Over the past year or two, I’ve built several NFC audio projects, but I wanted a more polished and streamlined version with an unobtrusive form factor.

Task

Design and build the thinnest possible NFC audio player.

Action

• Started with a Raspberry Pi 4 and removed all unnecessary components:
  • Unsoldered the USB 2.0 ports
  • Unsoldered the USB 3.0 ports
  • Unsoldered the Ethernet port
• Used an Adafruit PN532 NFC board for NFC reading.
• Mounted it upside-down on angled standoffs to get it as close to the surface as possible.
• Created a 3D-printed enclosure in Blender that is just tall enough to fit the Pi, NFC board, and exposes the USB-C power and audio port at the back.
• Printed the enclosure using white PLA on an Ender 3.
• Programmed a simple Node.js service that listens for NFC tags and launches Spotify playlists using Mopidy and Mopidy-Spotify.
• Containerized the application and used https://www.balena.io/ to manage the device and deploy updates.

Result

Latest Version

It turned out very thin and sleek. The NFC board sits just beneath the surface, allowing it to easily read tags. I printed on card stock and embedded NFC tags into them for different playlists.

Second Version

I secretly built a second version for my brother immediately after finishing the first. This one was embedded into the wooden frame of an existing speaker. I removed all the original internals and replaced them with new speakers, a Raspberry Pi, LED status lights, and an NFC board. Once reassembled, it looked completely stock from the outside.

First Version

I collaborated with my brother to make a gift for our dad before Christmas. The device played music offline and had NFC tags embedded into 8-track cartridges. Although I don’t know much about speaker design, it was a fun challenge to design and build an enclosure entirely from scratch.