This puzzle was designed combining the cylindrical shapes of the "0005: Brunnen-Puzzle" and triangles. In the first picture you see the seven puzzle pieces being packed in the stretched hexagonal box:

There you just see the top layer of the pieces, so I put them out of the box:

Now you see that the puzzle consists of three layers: the top and the bottom layer each uses cylinders, and the middle layer consists of a set of 10 small triangular prisms. The seven pieces are designed such that (for sure) there is only one possibility to fill the box flat with all of them. Although there are 'only' seven pieces the puzzle itself is quite difficult.