The project House of Mice was developed by Karina Schaapman as a decoration for this children's book. It is made of cardboard boxes. To furbish the interior, Karina used authentic fabrics from the 50s, 60s and 70s and various types of waste material. The House of Mice has a front, side and rear wing and has over one hundred rooms, plenty of corridors and outdoor spaces. The mice inhabiting it have been designed and produced by Karina. During the construction and furnishing of individual rooms, stories for the book with Sam and Julie as main characters emerged spontaneously. In the Netherlands, thanks to the huge international success of the book, more stories about Sam and Julie are being issued. In the Czech Republic, they will be published around Christmas 2016 and spring 2017.