I need the experience. You need the model...

I'm designing for my "someday" machine, for which I decided long ago that roads will be represented no smaller than 1/8".

That turns out to be something like 9km on a side, but it depends on how "shallow" the relief is too.

(I just did an area around Amarillo, TX and had to multiply the Z dimension 10X so you could see "anything." All the "flat" that was left over after making the Rockies was stored in West Texas. Don't know if you knew that.)

Something a couple of kilometers on a side will probably make a good model. (You could create a public map of the view you want in googlemaps and post the link?)

Here's a MeshCAM render of my model of Devil's Lake, WI to give you an appetite. 18" wide x 0.5" deep.

Deeg

Chris proved the model's viable (this morning at 3 am, not recommended).

10 hours machining time, but using just a 1/8" bit, and doing X-then-Y passes.

Still, it looks more like a lake at a state park than, say, a monkey.

Chris,

You ebay, don't you? Throw it up on ebay.
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Dang