Print it, in color if possible, double-sided. If you cannot print it double-sided, print only the first page. Then arrange the four pieces without overlapping to make two identical shapes.
These pieces are the four pentiamonds. This puzzle is one of two that appeared on Ed Pegg's website Mathpuzzle.com in September 2008. The other was similar and used triaboloes.
You can buy a sturdy hardwood or acrylic copy of Body Double from WoodWonders Online.