Retrieve elevation data from coutour line file

I am trying to create a 3D model of a section of Rhode Island.  The plan is to scale it and machine it from baltic birch for a display.  I have been successful in parsing all the relevant sections of the USGS contour files for the state. My problem is that I do not know how to pull out  the elevation data (which I can see) and to translate each of the polylines in the z direction.  This a set manipulation question, not a meerkat problem as far as I can tell.  If I am going about this in a crazy way please comment.