There is one piece that stands out as the trickiest. Find it and start with that one.

It's the zigzag-shaped piece that cannot be placed flush against the edge on any side. It always occupies at least two "levels" of the triangle.

There's another important piece that shouldn't be left until the end.These two challenging pieces have only a limited number of ways they can fit together inside the puzzle. Start by experimenting with their positions.

It's simply the largest piece.It's the long, straight piece with a small triangle at one end. It belongs in one of the corners of the triangular base.

The next challenging pieces look very similar to each other and are the largest among the remaining pieces.Again, they have only a few possible positions. Once you've placed them correctly, the rest of the puzzle tends to fall into place.

The complete hexagon touches both of the two large key pieces.

The hexagon with the missing section also touches both key pieces, but from the opposite side. It is also interlocked with one of them.