contour mapping

Hello all--I've been wanting to CNC machine a scaled "relief map" of
the wheat and cattle farm where I grew up in North Central Kansas
U.S.A. This consists of several hundred acres of rolling terrain
including the farmstead. All I have left are the memories and an
aerial photo of the buildings.
Would anyone have knowledge of what it would take to utilize data
from the U.S. Geological Survey (URL below) to program the contours?
I would like to construct scale models of the buildings from memory
and place them on what I envision to be about a 24" square "map".
The various "ponds" filled with something to simulate water would top
it off! Can anyone please help me? Thanks. Nelson
http://navigation.helper.realnames.com/framer/1/262/default.asp?
realname=U%2ES%2E+Geological+Survey&url=http%3A%2F%2Fwww%2Eusgs%
2Egov&frameid=1&providerid=262&uid=30116898