Diorama Construction question

I would put Styrofoam down first. It provides a good base for the Celluclay. It will also allow you to give the ground some shape or form, unless you want it flat. Its easy to poke holes for tress and stuff in the foam too. I've been using Gorilla Glue to attatch foam. It works really good. The only thing to keep in mind is that it expands, which can be good because it's almost like a foam when it expands.

Thanks a bunch for the reply, Dave. That makes alot of sense.

I love Dave Town btw. I can see small hills to work with styrofoam but how did you achieve those beautiful bigger hills ?

 If my diorama turns out even a third as well as your town I'd be a happy camper. 

I make the bigger hills by stacking up the foam. I put a film of glue on the foam and drive big tooth picks through it to hold it while the glue drys.

I took a lot of construction pictures. They might give you some ideas.

http://public.fotki.com/DaveInTheHat/davetown/construction_pictur/