Stiles' room has slate blue walls with white window trim. His bed is a twin, with a black storage headboard. His desk is a plain white tabletop, with no drawers. It looks like an Ikea Hissmon with metal legs. The desk is just big enough to hold a small desk lamp, printer, and his laptop.
In Episode 2x12, he has a telescope by the window. And a boogie board up against the wall.