One block wonder
 

Has anyone ever used more than one fabric for a one block wonder ??

If they blend together(color wise) I would think that you could. I'll be anxious to see what others say.

As long as the colors blend well, it should be OK. The difference between a OBW & a Stack & Whack is that the object of the OBW is to have the blocks flow from one to the other, almost blending. S&W have sashing or other fabric that separate the blocks into individual designs.