The MusicBox is a screen-free audio player for children. Place an NFC card on top and the story or the music starts, take it off and it stops. No subscription, no account, no screen: your audio lives on standard NFC cards and every part can be replaced.

This page is the 3D-printed enclosure of the V4 prototype, built around the HermitX development board (ESP32-S3).

What you print

• Body (V4.1): the main shell that holds the board, the speaker and the battery. It is one multi-material print made of four parts:

  • Back: the rear part of the shell.

  • Middle: the central part of the shell.

  • Window: the side window the LEDs shine through, in a transparent filament.

  • Fins: the inner fins between the LEDs, in a dark filament, so the light of one LED does not spread into the next.

  Print the 3MF to keep the four parts and their filaments. The STL is the single-material fallback.

• Top: the front panel.

• Insert: protects the battery and guides the NFC card when you insert it.

• Volume knob: the cap for the rotary encoder.

• full.3mf: all four parts assembled, to look at the box, not to print.

What you need

• HermitX N8R8 development board (ESP32-S3). The NFC antenna and a speaker ship with it.

• Rotary encoder: Bourns PEC12R-3220F-S0024

• 4 metal push buttons, 12 mm, momentary (not latching)

• LiPo battery 3.7 V 5000 mAh (955565), Adafruit bq25185 charging board with 5 V boost (part 6106), SS-12F15 slide switch

• microSD card, 8 to 32 GB, FAT32, and blank NTAG215 NFC cards

• Optional: PUI Audio AS04004PO-2-R speaker for a fuller sound (4 more screws and inserts)

• Fasteners: 8 to 12 M2.5 x 5 mm countersunk screws with brass inserts (3.5 mm OD, 3 mm long), and 4 M3 x 8 mm countersunk screws with M3 brass inserts to close the box. The inserts are pressed in with a soldering iron.

Cables and full references: BOM and wiring.

Print settings

• Prusa MK4S, 0.4 mm nozzle, 0.2 mm layers, PLA (PETG works too)

• 15% infill, 2 perimeters, supports enabled for the body

• Print times on the MK4S: body about 4 h (about 110 g), top about 1 h, knob about 15 min

• Colors: in the body 3MF, assign a transparent filament to the window and a dark filament to the fins. Back and middle take the main color of your box.

Build it in 4 steps

1. Print the parts.

2. Press the inserts in, then mount the board, speaker, buttons, encoder and battery, following the build guide.

3. Flash the firmware straight from your browser, nothing to install: Flash the firmware.

4. Install the app, add your music and stories, link each playlist to an NFC card.

This is a prototype and it is still evolving. Makes, photos and feedback are very welcome.

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License: CERN-OHL-S v2 (strongly reciprocal open hardware). You may print, modify, share and even sell hardware based on these files, as long as your modified design files remain open under the same licence, with attribution and a link to your source.

Official source: github.com/The-Open-Music-Box/enclosure

Trademark: the files are free; the product names and brands of The Open Music Box are not. Compatible or derived boxes may not be sold under those names, which are reserved for certified units.