Flow Polycarbonate plastic , magnetic wall diary. Design: Duo Design specializes in design, development and production of its own line of interior products. Simplicity of design, subtle details and the application of high quality materials lend the products an unmistakable ¨duodesign¨ signature. The collection is sold in a large number of countries and various designs from Duo Design are included in the collections of museums of modern art and design.