Bowls made of mushrooms, cups fashioned from seaweed, and detergent-style pods for food: Designers are creating ephemeral alternatives to plastic. But are we ready to accept them? Around tables strewn with Exacto knives, bowls, cutting boards, tape, funnels, and bags of hemp powder, mushroom parts, and sugar, a dozen graduate students from the packaging and industrial-design departments at Pratt Institute, in Brooklyn, New York, brainstormed. Their brief? To create new forms of food packaging to replace the unsustainable designs upon which modern life seems to depend: single-use plastic beverage cups, lids, straws, and bottles. Focusing on the long-lived detritus that typically accompanies take-out meals, the students baked and 3D-printed straws made of sugar and agar—a gelatinous substance derived from seaweed. They hand-shaped bowls from mycelium, the threadlike roots of mushrooms. One team designed sheets of black plastic that folded into take-out containers (seen in image above) and could be returned to a collection point, sanitised, and reused ad infinitum by a consortium of take-out chains. Another duo crafted an ingenious paperboard box with a fold-it-yourself fork/spoon ...