Comment by OkayPhysicist

The best machine I've seen so far is one in my local gas station, where there's just a surface and a camera. Toss whatever you want onto the surface, all haphazard like, check that the screen agrees with reality (it always has so far), and bump your watch/phone/credit card and walk out. We're talking substantially less than 30s, oftentimes less than 10s.