Frost forming on a 3D-printed leaf (IMAGE) Northwestern University Caption Ken Park and his team 3D printed a maple leaf and filled it with coolant to observe how frost avoided formation on concave regions. Credit Northwestern University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.