If you're after accuracy, don't forget that the Earth is about 20km shorter in radius through the poles than it is through the equator (it's roughly 1 part in 300 flattening through the poles). That pretty much swamps the 6km altitude of Kilimanjaro at the equator. SJS also forgot to mention that 90+% of the Earth's surface is less than 1000 meters is elevation (assuming that you want sea level to be roughly flat). That's very approximately 1/400 of an inch; I've always found 400 grit sandpaper (1/400 inch particles) to be delightfully smooth to the touch.

The biggest problem that I've always had with paper is that it changes size with humidity (typically a few percent). I live in a desert that has lots of indoor humidity in summer and almost none in winter, so I've watched quite a few projects crack or wrinkle over the years...