Show HN: Marelleo, an open-source story box I built for my kids using ESP32

Marelleo is a screen-free story player built for young children: place a figurine on the box and it plays the associated audio; remove it and playback stops. Its creator wanted the simple interaction of commercial story boxes without their closed catalogues and ongoing content purchases, and also used the project to learn electronics from scratch. An ESP32 handles audio playback, while an NFC reader identifies tags attached to wooden figurines - or any chosen object - so families can decide which object triggers which story. The account emphasizes how breadboards made early experimentation forgiving, then traces the move to soldered perfboard and a custom circuit board as the device became something children would use every day.

Building for children forced attention to hazards and durability. A miswired volume potentiometer caused a short circuit and smoke; a battery wired directly to the charging board left the box permanently on, prompting a more serious approach to power safety. The children also twisted the volume knob until its wires tore off, leading to a redesigned, thicker 3D-printed enclosure with components held by plastic and reusable brass screw inserts. The final electronics consolidate power, charging, amplification, storage, and connections on one PCB. AI assistance helped develop the schematic and check component details, while the creator manually routed 491 copper tracks in KiCad. The project’s central lesson is that making a working prototype is only the start: a child-ready object must also be safe, sturdy, repairable, and inviting to keep in the home.