Escher Cubes

The puzzle consists of 12 differently shaped laser-cut pieces. The pieces cannot be turned because they have the pattern on one side only. The piece with metal pins can be placed in 10 different places. The holes for the metal pin are scattered in the bottom of the frame. The task is to place all the pieces in the frame so that no empty spaces are visible. Ten different solutions, although there may be several solutions for each of them. Very demanding!