If you found yourself...unsettled...by the notion of quadrocopter construction crews, you may want to skip the videos below. The Flight Assembled Architecture exhibition, which opened yesterday near Paris, is using a squad of four tiny quad-rotored aircraft and a sophisticated tracking system to assemble a six-meter tower out of 1,500 foam blocks. To make the tower, a 'copter picks a brick from a dispenser and flies it to coordinates determined by a digital blueprint and the room's motion-capture system; when its battery gets low, it returns to its perch and is replaced by another. The system averages about one brick per minute.