When I assembled my dollhouse kit "De Cameleon"  from Karweipost back in 2007
just one chimney (the square one on the roof at the back of the house) was part of the design.

However, I wanted a hearth in almost every room of the house,
so I added another chimney to the right hand side of it.

I later improved the top of the chimneys.

The one at the back of the roof got a better top
by adding some paper covered by plaster.

To enhance the one on the side of the house,
I made some pipes out of wood and paper, stained them
and glued them in place on a layer of plaster.

And this is how the roof looks right now....