Before I applied the final weathering, I wanted to construct the base to allow me to integrate the tank with its environment. I dove into my stash of bases I'd collected over the years for various figures and found one that would fit the scene I had in mind. I first scored the top surface with a box knife so that the glue would better adhere to it.
I then carved a piece of florist foam to the basic shape, masked off the sides of the wooden base, and glued the foam to the base with scenic cement (which I suspect is nothing more than a higher-priced white glue with a matte agent added).
I mixed a batch of Aves ClayShay and applied it with a spatula to the top surface of the foam. This is some of the best ground material I've found. Depending on how you mix it, you can use it either as a clay (thick) or as a mache (thin). When it was partially dried I pressed the tank into the surface so that it would appear sunken into the ground and added a few scale rocks to the surface.
Next up will be painting and adding additional ground work.