kajuSPIELBAUSTEINE brings authentic stone feelings into children’s rooms. As a civil engineer and stonemason, founder Kai Bellinghausen deliberately chose solid natural gypsum for authentic, tactile experiences that feel heavy, cool and smooth like a river pebble.
At the heart of the building blocks is the innovative loose joint connection. It enables hands-free construction of arches that hold together solely through pressure and balance. Children intuitively grasp statics and gravity through free play, and balancing trains their fine motor skills. When a structure collapses, it awakens their spirit of discovery: What holds? What doesn’t? This not only encourages children to find clever solutions, but also promotes creativity and resilience through play.
kajuSPIELBAUSTEINE are a conscious contrast to the digital world: a real experience that arouses curiosity and encourages the development of new ideas. 100% craft made in North Rhine-Westphalia, Germany, 100% plastic-free and awarded the ‘SpielGut’ seal of approval and the ‘Bewegte Innovation’ (Moving Innovation) award.
Awards
2017 quality seal ”spiel gut“ for kajuBOGENBAU Starter-Set
Moving Innovation
with Kai Bellinghausen, founder kajuSPIELBAUSTEINE
Why did you start “kajuSPIELBAUSTEINE”?
It all began with my curiosity as a stonemason. To truly understand the structural mechanics of historical arches, I built models. But when I saw how enthusiastically children used these ‘technical’ stones to build entire worlds, it became clear to me: This is my path. I want to give children authentic materials that allow them to express themselves, playfully test their limits, and experience the power of finding their own solutions. Every structure they create is a personal achievement – a testament to their own skill.
What is special about your play building blocks?
Unlike interlocking bricks, we rely on loose connections. This is vital because it allows children to truly experience the physics of the arches and find clever solutions of their own. The curved shape makes the stones incredibly versatile: whether used for organic flat patterns, arched worlds for wooden figures, or marble runs – anything is possible. This ensures they offer constantly evolving challenges for ages 3 to 10. From the very first simple layouts to complex construction, these stones accompany them through their entire childhood.
When and where was “kajuSPIELBAUSTEINE” founded?
It was 2015 in Hildesheim. I was writing my bachelor’s thesis on the structural mechanics of arches and domes while simultaneously founding the company to showcase the concept at the Toy Fair in Nuremberg. The feedback from retailers was fantastic! However, setting up my own workshop was then delayed by six months for the most beautiful reason of all: the birth of my son.
Where do you produce your natural building blocks?
To this day, I still craft the blocks in my own workshop with great passion and dedicated support. The hands-on work gives me the mental space for new ideas, but playing alongside children in local daycares is just as inspiring. In fact, it is often the children’s own creative solutions that spark new play concepts or expansion sets
What do you do when you ARE NOT working, Kai?
I spend a lot of time with my family, tinkering on various projects with my son, and doing sports out in nature.
kaju SPIELBAUSTEINE
Kai Bellinghausen
Libellenweg 3
53639 Königswinter
Germany
Tel.: +49 176 444 30 30 26
