The Three-Piece Knot

What do you need to make this puzzle? Three pieces of wood 3 cm x 3 cm x 12 cm long. Measuring from the centre, on each piece draw the sawing lines 3 cm apart; the indentations must be a little bigger than the thickness of the pieces and sometimes half the thickness. Carefully examine the figures opposite. The middle part of one piece must be filed round. The indentations in the bottom piece in the diagram are each half the thickness.

When the three pieces are ready, try to fit them together to create a figure like that in the example shown here. Don't look at the solution too quickly, because it's more fun to solve the puzzle yourself.

Solution (not for the tenacious)