Meet the littleBits Synth Kit: a educational kit that lets you build a modular analog synthesizer using 12 modules that snap together magnetically. It lets you experiment with various sounds and build a customizable, modular instrument. The instruction book covers 10 inventions, but you can find plenty more online.
The kit includes speaker, oscillator, keyboard, and other bits. You don’t need any soldering or wiring to get started. Yet another fun, educational kit for kids.