Inspired by the work of several others on the Secrets of the Third Reich forums, I have begun a 3D board mounted on two MDF panels.  My plan is to use foamcore board, spackle, and much of the bits and pieces of garbage I have saved over the years, including computer cooling fans, wires, gears, pipe sections, and various random plastic detritus.  Painting on the figures has also past the primer stage.