Kevin meets Kevin McCabe who wants to build what may be the largest Cob structure in the world. With 6 metre-tall walls, McCabe fights a battle with the weather and his implausibly small 350,000 pound budget. He plans to form the huge property out of two vast curved roundhouses - the largest of which is inspired by the natural geometry of a snail shell - connected by glazing and topped with wildflower meadow roofs to mirror the surrounding countryside. However, the project involves mixing and laying a mind-boggling 2,000 tons of cob, all during warm, sunny weather - and the sheer scale of the task soon becomes clear.