Reply #16: Depends rather on what was in the 'kit', doesn't it?

[Igel]

If it contains the usual medicinal grade peroxide and fingernail polish remover, then it might be real or it might be fake. Assuming the peroxide-acetone explosive was the goal.

If it contains the materials in a grade sufficient for actually making an explosive, you're pretty much left with either government or having it be real. I doubt most people would risk going out and tracking down the materials--something that would certain attract attention at this point--just for a lark.