I cut several basic shapes out of felt and my kids make pictures with them all the time. Inexpensive, easy and fun. If you want a background, use spray adhesive to glue a large piece of felt or flannel to some foamcore or homosote. Or just thumbtack it to the wall. Pellon (interfacing) also works, too - and is incredibly inexpensive. And Pellon can go through your printer!
Next I think I'll make a felt tangram.