My first idea was to just create urban areas and streets on the styrene sheets I can get at my local art supply store, so I could create modular "tiles" which I could string together to make whole cities, if necessary. So I bought a thick one (.118) to avoid future warpage. I gave it a spritz of light gray primer and was ready to go:
However, it occurred to me that the road tape laid on top of the styrene sheet would give me roads at a slightly higher level than the surrounding grass areas, yards, etc. As we all know, even in the old sections of town, the streets are at a lower level, even if only slightly. Hmmm, back to the drawing board.
So, I decided that the cure was to use the thick styrene sheet as a base and overlay a thinner sheet (.40) as a top surface from which I could cut out streets, giving me a lower elevation on which to run my cobblestone street tape. So I duly cut out my streets and I bonded the top sheet to the base:
Unfotunately, after the primer, it very quickly became obvious that the tape just wasn't going to work. There was absolutely no way to get it to conform closely enough to the curves of the roadbed. So it seems there's only one other, labor-intensive alternative: scribe the roadbed with an X-acto knife, much as I wish there was a faster, easier way. Once I get over the roads hurdle, the actual landscaping should go quickly and promises to be a lot of fun. More when the roads are finished in a satisfactory manner.
PostScript: No, my scribed lines are too uneven and wander around too much. I'm going to have to think on this some more. But I still feel that styrene tiles are the basic building block.