Tapea big piece of paper on top. Cover your child's clothes with a large old shirt or apron. Have your child put the paint on the paper with her fingers. Let your child express himself. Some children will use large, wide strokes, others will focus on small spaces.
Some artists create art from old junk, things they have found on the beach or even at dumps.
Go on a treasure hunt inside to find other things such as scraps of paper, buttons, pieces of cloth, ribbon. Look for some heavy cardboard or wood to use as a backing. Have your child lay out the materials in a design on the backing. Have your child move things around until the design is what she wants. Using a heavy duty glue, have your child glue the items on the backing.