We're not entirely sure why people keep trying to bring back Smell-O-Vision, although Keio University's success in printing scents using a modified printer gives us hope that this sort of thing might someday be somewhat feasible -- and useful. It works by using an off-the-shelf Canon printer that's been given a "scent jet," Kenichi Okada told New Scientist. "We are using the ink-jet printer's ability to eject tiny pulses of material to achieve precise control." The scent dissipates quickly, after one or two human breaths. And while specific scents can be printed, there is as of yet no way to build a general purpose device. According to the University of Glasgow's Stephen Brewster: "We don't yet know how to synthesize all the scents we want. There is no red-green-blue for smell -- there are thousands of components needed." That's OK with us. In our experience, it's usually better that people keep their smells to themselves.