Reinier de Jong originally came up with the concept for the REK in 2008, and now he presents an improved version of the adjustable bookcase. In its default beginning shape, REK seems to be a solid block with a zigzag pattern engraved, but once the pieces are shifted, storage spaces are created. For those of us who do not have a permanent library collection, we never know when we might need more space. The new shelving unit is more lightweight than before and includes stops that prevent users from sliding the pieces too far.

[via Design Milk]