Hello Everyone,   I'm trying to create a chimney that tapers.  (see picture 2)  I've drawn the walls, which represent the wider portion, on the first floor and the walls, that represent the more narrow section, on the second floor.  I need to create the transition piece between (see picture 1).   I want the transition piece to perform much like a slab so that the horizontal lines are invisible when rendering Hidden line.   My questions are:   1.  What is the best wa