I actually sort of did this (but I cut them w/ a CNC router rather than 3D printing them).

https://imgur.com/a/fMy19 is the finished product; http://www.thingiverse.com/thing:1524543 are the files I generated and used. They aren't truly accurate maps -- they do have the elevation exaggerated to be more visually interesting, but it's consistently scaled. Some people have gone on to print them w/ 3d printers (rumor is they're on the wall at Makerbot now).

Already has! I made Terrain2STL [0] a couple years ago to do just that. It converts STRM topo data to the STL format.

[0] - http://jthatch.com/Terrain2STL/

Nice. Could you 3D print the entire earth as a globe? :)

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).

You are absolutely right, it hit me as well after posting the questing. The elevations would have to be vastly exaggerated for a globe

There are a couple people who make 3D printed full color maps on Shapeways. They are actually pretty cool:

http://www.shapeways.com/shops/tinymtn

http://www.shapeways.com/shops/smartmaps

Thanks for the hat tip! TinyMtn is my fun hobby, and I've been making high-resolution 3D printed maps from USGS and SRTM1 data for over three years now. I'm just getting into the extensive LiDAR data now, too. The process is: download the highest-resolution data I cna find from USGS's National Map Viewer, process with GDAL, convert to a triangle mesh (custom tools), and then upload to Shapeways or convert to GCode for my XCarve. Some of these prints, along with CNC models of Meteor Crater, Telluride, Mt Fuji, Mt Hood, and Crater Lake are on Etsy: https://www.etsy.com/shop/TinyMtn

Here you go

http://jthatch.com/Terrain2STL/

You can get low resolution digital elevation models over the US from the USGS or NASA. From there you can triangulate and generate an stl file fairly easily.

There is no reason you can't make a 3d map, by tracing the contour lines...