As noahnoahnoah's comment alludes to, there is kind of a problem with elevation differences on Earth being small. For example, the vertical distance from sea level to the summit of Mt. Everest is only 0.1% of the Earth's radius.
If you made a globe with a 1 foot diameter, Mt. Everest should then be on about 0.2 millimeters above the surface (if you choose to represent sea level as the surface).
Edit: this problem is less dramatic if you make either models either of local regions, or extremely large models (because relative to the size of a region like the Bay Area, the highest elevations in the region are fairly high).
