"Unlike traditional plaster and fiberglass casts, this one is made of nylon, which means it is lightweight, waterproof and recyclable. It is also thin enough to fit under sleeves and covered in holes that allow airflow and fingers in for scratching.
Evill developed the cast for a class at his university, inspired by a personal experience. “I had broken my hand that weekend and was very annoyed with the cast I had on, as it was the first time I had a cast,” Evill said in an interview Friday." from source: http://gigaom.com/