Has anyone ever seen this stuff? In class the other day one of my professors moved the sliding chalkboards around to reveal the behind-most chalkboard. As he was writing/erasing you could see the board ripple suggesting it was made from a much thinner than normal chalkboard. I am getting sick of my whiteboard not erasing and like chalk better, so I was thinking of sticking this stuff over my current whiteboard. Where does one locate such a product?