How to get top and bottom curves from Surface walls?
I can not get component Brep | Plane to work. 
Is there a better way to do it?
I tried to lower/rise plane but it did not make any difference.
Any help will be appreciated 
UnableToExtractEdges.gh (21.4 KB)
@Jakinta thanks a lot for help, what are 0,-1 inputs to get extremes from each surfaces? as we sampling via 3 levels for each surface?
Indices 0 and -1 are there to extract first and last item on a list. In our case lowest and highest coordinates, since they were sorted previously on Z-values.
