MP3 player design from Dooba.io:

Shiva: MP3 player for the masses

Based on the ioNode, Aecho and Nomad modules, the Shiva allows browsing & playing MP3 files stored on any FAT-formatted MicroSD card with audio quality up to 128Kbps.

The actual Shiva board itself is quite simple, featuring an MCP23008 from Microchip for reading the 7 buttons, a DM3D-SF MicroSD card socket from Hirose and a 128×64 OLED display from Adafruit.

To keep everything neatly together I needed an enclosure. Being lucky enough to own a half-decent 3D printer I decided to keep things minimal but functional. Who needs glue and screws when you can go for a press-fit case?

The code for the Shiva MP3 player is available in the Dooba Firmware SDK under /src/shiva.  Schematic and board are available in the Dooba Hardware collection.