At a backyard barbecue recently, my friend set up an inflatable wading pool for guests to dip their toes into. She had hadn’t yet figured out what to do about lighting so as the sun set, the yard became spookily dark. Her boyfriend, a lighting designer and all-around handy guy, went to the kitchen and returned a few minutes later with white plastic mixing bowls and tealight candles. He placed the candles in the bowls, lit them and carefully set the bowls in the water. For the remainder of the night, the makeshift floating lanterns gave the party a soft, warm glow.