I wanted the same style chimney as on the box. So, I first painted the inside edges of the openings on each chimney side. I painted the backs to match, in this case, black.
I glued on the backs at the same time I put all the sides together so the glue was still wet for me to position everything just right. I clamped everything and set it to the side. Make sure you assemble your chimney in the right direction. The four openings are towards the outside of the dollhouse and the two openings face the roof. Make sure they are to the top of the chimney. I assembled the flues and glued them to the chimney top.
While they dried, I glued on the top chimney trim to the chimney. I wanted the same kind of texture as on the box so I made some quick mortar/stucco using a mixture of spackle and gray paint. I applied this mix all over the top trim.
I then printed out bricks from my computer and using a glue stick, I wrapped it around the chimney to give it a bricked look. I cut out the openings on the sides with a sharp craft knife.
I then painted the chimney top and flues black and inserted them into the top opening.
I finished the third floor staircase railing. It goes on in the same way that the first floor one did.
I used wood strips to cover all of the back floor and wall edges. I did this for both open sides.
I had enough strips left over to apply baseboards to the first and second floors.
I varnished the first and second floors.