Wal3d,

  I have asked before for a Knife or Cut tool but we didn't get one , oh well.

  There is something that people may not know about the Extract Along command, it works well with  polygons as well as edges. So select a group of edges, click the Extract Along command and click polygons and drag to extract edges and then  finally scale edges to be zero in the appropriate axis. 
  You can do the same for your edge sample but you would have to weld the result with a very small tolerance as you would have vertices on top of each other at the Top and Bottom of your sample object.
  Here is a pic of what I mean. Hope this helps.