Thanks. Of course, the markers were just the quick and easy way to make the original pencil visible.

I think my next step is to use hot glue to attach styrofoam to the paper in the dark areas.

I'll build that up then cover it with acrylic molding paste. Using crumpled paper and glue would be too rigid and leave the map slightly curled. The hot glue and acrylic should be flexible enough that the whole thing will still lay flat.

Any ideas?