Cover with contact paper, inside and out. Or cover the outside with brown grocery sack paper and decorate in your own style. Put each child's name on the outside. Add large plastic needles available at craft stores for crewel work and use the foam trays to teach your child to make designs using yarn. 3-D clouds to a landscape, or texture to a collage.
Plastic bottles become funnels and scoops for the sandbox., bathtub, garden and beach.
Spend a little time at your library with a crafts for children book to get more ideas. Stock up on papers, paints, markers, etc. Use what you have. Spread peanut butter on the pinecones and hang them on trees and bushes in your yard for the birds. Roll them in birdseed if you have it.