Ooh, ooh, here’s one! A morphing bit driver: it’s a shapeless mass of metallic patricles, more liquid than solid. You stick it in any screw, then press a button. The mass hardens and turns into a solid driver for that exact screw head. I suspect this would be utterly impossible without batteries, but hell, isn’t it worth it?
I want a button that shifts red traffic lights into green lights for me.That might even be doable, but if that solid metal mass that fits perfectly will also be strong enough to withstand the necessary torque for actual work is a question. An energy source would be needed to make heat.
I don't know what it's called, but here in the States, many emergency vehicles already have such a system installed that changes lights.