By placing the "key" so that it overlaps the end projection of the arm a space is left at the centre, and means is thus afforded for getting in the three cross parts on the remaining two arms.
This practically ends the puzzle. While the "key" is in its overlapping position the parts may be separated, but if it is turned round on its narrow neck, so that it is in exactly the same position as the other five small cross parts, it locks the whole thing so tightly that nothing but sheer force could loosen the twenty-one pieces.
So far as the order of putting together is concerned, there are many equally satisfactory ways, these being determined by the ease or difficulty that one experiences in holding the half-finished puzzle. It all comes to the same in the end, and the "key" must be placed on one bar before the last three arms can be completed. The "key," moreover, must be on one of the bars where a gap is left at the centre, and not on one where lies flush against the central arm as in .