We have a friend who got an air purifier that he could never figure out how to work, but then our friend is obviously not the brightest bulb in the chandelier. The result is that there is more dust on the thing than in it. Would that he had Joseph Kim’s Daan (Korean for column.) The prototype consists of simple disks that combine to handle any size room. Single ones can be used when you travel. The Daan is constructed of brushed aluminum and fabric.