BoxWall is made out of concrete. The boxes are only 10 mm thick and have a round cavity on two sides where a marble can be placed so that the boxes do not move when placed on top of one other. In the front, there is a 3 mm groove where an optional material can be inlaied. The boxes have a near endless range of applications, including legs for a table, a lamp, storage or even a partition wall. More pictures here.