Marta Musik Maschine
Before doing anything, checkout the associated blog post series at martamusikmaschine.com.
Marta Musik Maschine is a DIY, RFID enabled, multi-purpose, audio and light device for kids. It's open source and you can build one yourself. It's not hard at all, I promise.
This repository contains all the code needed on the Raspberry Pi, a KiCad project that enables you to etch/order a PCB and a few stl models that you can print on a 3D printer.