I am working on a new property where we will need a home and several buildings. Detailed Topo Elevation data seems hard to find as the area is rather rural.   Having built a spreadsheet of test XYZ data and importing that into CA/Home Designer worked quite quickly to produce a terrain surface.  Since that worked well, I would like to take a handheld GPS and walk the property and develop a elevation point grid to have a relatively accurate terrain model to design on.   The elevation over the pr