A lot of rice paper, foil, and heavy paper, too. After the procession, they are lifted and walked down a long flight of steps from Wat Xieng Thong, where the procession ends, to the Mekong River, where they are set adrift. That's pretty magical. I've seen beached fireboats later, so I imagine they are eventually retrieved by someone and reusable materials taken, though that is conjecture. The spectators also, many of them, float small boats, made with banana leaves, flowers and having lit candles, into the Mekong, as a gesture of renewal and hope. I'm holding one of those "Krathongs" in the picture I included. Disturbingly, though, many of the Krathongs these days are made with syrofoam, a further stress on an already stressed Mekong.