Really interesting. The built-ins could be made with some regular shelving units and crown molding. The bed/couch doesn't necessarily need to be built in (a simple removable day bed would probably also look nice) but I love it like this.
What a wonderful warm "glow" of candles! They sure can set the mood and give this monochromatic setting a cozy feeling.
A company called Blandito has designed a circular, foldable pillow that can be manipulated into many shapes (bed, chair, cubbies of different kinds.) Extra larges for adults as well as children's size. I can see this being great biofeedback for sensory averse/craving children. Too bad it's still in the design phase!