As a kid, I loved to disassemble things like radios, RC cars orb bikes just to see how it works. Most interesting were the things that were designed (as in engineering) very clever. Probably one of the reasons to study mechanical engineering. I remember radios with ingenious ways to transfer the rotation of the knob to the translation of the dial. Nowadays, I rarely take a device apart, but watching some photos of it can still be interesting, e.g. teardown of an iPod Shuffle, Nano
or Touch