It's fairly simple to construct a way to see your own face. All you need is a high-grade color LCD or OLED display, a high-resolution digital camera, a power source, a few controls and a logic board. Too bad none of this was available before 2010, those poor ancients must have always wondered what they looked like.
You jest, but I've heard a tale from a local engineering college: they regularly give to the graduating-year students a task to design some system which, after you remove all the fancy wordings, is basically insides of a toilet cistern/tank. Year after year, the students keep producing astonishingly convoluted designs.
I once re-invented the whistling teapot while deeply engrossed in using Arduino for anything and everything. I had only saucepans to boil water with and wished they could alert me once the water reached temp, perhaps optically sensing the turbulance of the surface.
Well, if you put a lid on a saucepan (and you should, it conserves energy and makes water boil faster) you can detect it clattering when the water starts to boil! So you don't need any optical input, a microphone will suffice ― which is cheaper, too. Filter out the low frequencies of water humming, amplify the rest, and you got a (not-so-nice-sounding, because it rattles, not whistles) boiling point alarm!
