Thanks for the comments everyone.
David,
The rusting on the Panther was done with multiple coats of 'Rustall" on top of various thicknesses of 'Cast-a-coat" (basically a very fine sand adhered to the surface)
JB,
"
can't wait to see the whole finished!"
I should have been clearer in that these photos are of older dioramas of mine

I found a whole file of misc. photos on my computer!
Here is the 'finished' diorama, "Poland 1958" that you commented on:
Cheers,
Charles