It's quite possible... but before anyone jumps in to make it ... have you tried PushPull? Group your contours and add a large flat face for them to intersect with - adjusting their extents etc as needed. Now you can PushPull the face between the contours to the required level. Other matching contours can be 'matched' within PushPull by picking a point on a previously made one. If you know that your contours are at 5' intervals then PushPull one 5' and subsequently a PushPull with a double-click on a face will lift/drop that face by the last used amount, double-click again and the amount doubles, again and it trebles and so on... When done erase the side edges to remove the faces between contours... Sometimes a native technique can be as quick as using a custom tool...