Knock Knock is a simple and versatile shelving system by German design company Hoj Studio. The unit is modular and consists of the tree basic components that are attached to each other via braces. From these parts you can create a bookshelf, a kitchen cabinet, a desk with flexible storage, an entryway piece, and more. The combinations are endless. The Knock Knock shelving is made of solid oak and purposely left semi-finished, so you can personalize it further (or not). Check out the video after the break to see the assembly of the piece in action.