My son loves playing with these Smartmax magnetic building blocks, he makes wonderful creations with it. It builds really easy, the blocks feel great, the magnets are strong and playing with this set gives kids insight in how to create stronger constructions (with triangles!). I can really recommend it to all parents of kids with interest in constructing their own creations. But he wanted to build more and explore further and was asking me for extra parts that were not in his set and even didn't exist… yet. I'm a beginner 3d printer but tried to design the parts he asked and was amazed how well these 3d printed blocks came out. So I wanted to share these with others so they can also expand their sets with new possibilities. I use neodymium magnets of 10x5mm for the sides. I tested 13x3mm first but felt they were not strong enough. First I used small pins as connectors but then I discovered that chamfered cubes are way easier and sturdier and it feels feel great to push them in.