W and M Puzzlea

Can you separate the two M pieces, and put them back together again? This Puzzle is unique as it is very simple to put together but annoyingly difficult to get apart!
This puzzle cannot be put down and may cause frustration and irritation, hence the name ! However once the Menace has been mastered you can sit and watch others suffer with a most satisfying smile!!
The solution is simple in theory, just slide them apart. But not simple in practice! A lot of patience is needed for this puzzle.