"The first clue was that the top face was in shadow (darker)… that let me to believe that it was a concave surface. Then I figured that they all need to be connected." Artur then designed his solution using Rhino. So we're curious to see if Artur did solve it? Or is there another solution?
Update: Ulrich sez, "It has now come to our attention that Artur was not the first to figure it out. The original design and printed object were created by Ulrich Schwanitz who confirmed to us that Artur's solution is correct. Make sure to check the video, it will blow your mind even if you know how it works."