I'm finishing up the interior walls and trim. I'm leaving the section between the windows open for shelf space. The windows face NE and NW, making ideal light for a studio. There will be a wrap-around desk in this section.
The final step is to put blocking in the roof, then insulation, then the ceiling. I am going to go with fiberglass insulation due to its performance with moisture. The denim-cotton wouldn't hold up. For the ceiling's center section I am looking online at decorative pressed tin that comes in 2' panels. I am looking for a lightweight wood to use on the sides going up to the center.