The Sunbeam T-20 toaster from 1949 is the pinnacle of both engineering and design. You put the bread, or bagel, or pop tarts in, and everything comes out perfectly toasted. No buttons, no transistors, only a small knob to set preferred darkness. It knows it's ready when the radiated heat off the food causes a small bimetal component to expand at different rates, bend, and trip the release to raise the toast. Set it once on a piece of bread and it's the same level of toastiness for everything you put in there. And it looks space-agey and timelessly cool.