Printer manufacturers will happily sell us very cheap printers because they profit many times over from also selling us very expensive ink cartridges . But what if your printer no longer required ink and in return the paper it used was a little more expensive? More expensive paper may sound like a negative, but what if each sheet of paper could be erased and reused 80 times? That’s what a team of researchers at the University of California at Riverside managed to create: a printer that replaces ink with light , and paper that contains the dye it needs to form print, but which can also be erased and reused many times over.