Rustic

The back of the house is open and the floor plan is just one large room with a window on each end. The roof back is solid with no opening, and there is no attic floor, so those are features to consider adding. Only problem with that is how the siding is nailed in, all the rusty nail ends are sticking out into the attic interior space. Looks like an iron maiden torture device up there! Inside the house proper the nails aren't a problem because there is an inner wall covering them. This house is built with stud-framed walls, just like a real house.

Can you add studs and/or beams to the attic to cover the nails?

Possibly. They're pretty long and scary nails. I could probably bend them out of the way enough to add interior walls. After I get a precautionary tetanus booster shot... LOL

If this is to become the kitchen you referred to, perhaps you could create a herb, veggie, meat hanging/drying area in the attic and utilize the nails for that somehow. Perhaps hinge the roof so it opens and create a little hinged post to hold it open for viewing the food storage area.

Selkie, that's brilliant! A bunch of hams and sausages and such hanging from the nails...so cute! I love that idea.