GIRO

Here is a note from designer Volker Latussek:

There are 14 ways to glue together a cube and two half-cubes – created by cutting a second cube diagonally – using their two square faces. Each piece therefore has the volume of a double cube. Consequently, 9 pieces fit into a 3x3x2 box. GIRO demonstrates that it is indeed possible to fill the box with 9 of the 14 pieces – and that there is a unique solution.
The interplay of the triangular half-cubes in the search for the solution is truly astonishing. And you really do have to think ‘outside the box’ in the truest sense of the phrase.