or what is left of them anyways... Apart from the uranium cubes used (compare http://www.pbase.com/soenke/image/165061880 ), the B8 needed heavy water as a moderator substance, i.e to slow free neutrons sufficiently for initiating a chain reaction.
One of the reasons, the " uranium project" never took off was that the Third Reich never produced any of the key ingridients itself but simply stole them from somewhere else. The uranium came from Bohemia and the heavy water was taken from Norway. Adding to that, nuclear physics was deemed somewhat "ungerman" - many of the leading scientists in the field were jewish and thus driven into emigration. Last but not least, it had never been an orchestrated effort, unlike the Manhattan Project. Several research groups squabbled for the very limmited funding and scarce raw materials