Originally Posted by T. A. Gardner

Most of German's "secret" weapons and projects were largely, if not completely, a waste of time. Of course, the same can be said of many Allied projects too. But, the difference is that the Allies, particularly the Western Allies, had the capacity and economy to support projects without dire impacts on war production in general.
To compound Germany's problems in this area, the Nazi system of individual fiefdoms that the various personalities surrounding Hitler had made often competed for resources and had parallel developments going that duplicated effort. Also, the political connections of the leadership in the government and business sectors often outweighed common sense or economic reality.
A list of truly idiotic and costly projects include: