To completely transform a room without damaging the walls, apply a strip of painters' tape in the areas you'd like to cover, then apply double-sided carpet tape to the painter's tape to hold scenery.
Turn a room into a shanty by applying ripped cardboard, pages from old books, and sheet music to the walls. Hang dried weeds, bark, pieces of wood, and other found items with removable adhesive wall hooks and twine.
Shredded burlap, crumpled craft paper, or paper bags can be used to camouflage everyday elements such as doorknobs and windows.