I may be misunderstanding your project here... but if the goal is to create a 3D globe with elevations to scale then the end result will be a completely smooth surface. The diameter of the earth is 12,742 km. The elevation of Mt. Everest above sea level is 8.848 km. This represents a deviation of 0.07%. If the entire globe were 3 ft. in diameter then Mt. Everest would be represented as an increase in height from the smooth surface of the globe of 1/40th of an inch.

Obviously this is assuming you're doing things to scale, which maybe wasn't your intention after all?