I spent almost the whole of last Tuesday morning doing a soldering kit from Elenco toys which, when completed, results in a circuit that produces a siren noise similar to the one on European police cars:
This is my second Elenco kit, and they continue to be a bit of a mixed bag. On the one hand their kits do a great job of encouraging experimentation by having you complete a small project and then suggesting ways you might, say, make the pitch of a sound higher by routing current through different resistances. On the other, I have been repeatedly struck both by how poor the editing in their documentation is and by how sparse their explanations are, even for projects which are fairly advanced from a beginner’s perspective.
But I did enjoy this kit, and especially appreciated that it had special practice sections of the printed circuit board on which I was able to take my first halting steps in soldering before trying to complete the actual project. This is definitely something you could get for the little Feynman in your life!