Columbia engineers built a machine that deposited seven edible ingredients and selectively cooked the result with a blue laser. A digital recipe arranged graham-cracker paste as floors, walls, and ceilings; peanut butter and Nutella formed pools that held banana purée and strawberry jam, with cherry drizzle and frosting completing the slice. After seven design iterations, the printer produced the dessert in about 30 minutes without a person assembling it by hand.