Get creative with Gorgi's die cut, plywood wall art. See how great they look left natural, or paint or varnish them depending on your decor. The wall art can be applied to the wall with Blu-tack, Velcro dots or similar self adhesive product (depending on wall finish).
Try a collective set, of 6-9 pigeons for example, which look fantastic as an inexpensive art installation. Try flying the pigeons at different angles to achieve a dynamic look in your child's room.