Very Hungry Caterpillar Mobile. Hang 8" lanterns (1 red, 6 in two shades of green) with different lengths of fishing line. Use pipe cleaners for antennae, and construction paper for eyes and nose. Very cool in a children's library space.
Tree idea for Reading Area, tent... Options: attach some of the branches to the ceiling /or drape thin blue cloth for sky/night sky. Add white Christmas lights to the "sky" i.e. on the hanging fabric or wall ceiling.