Clothespin Math on a clothes hanger! Easy to make, and self explanatory. I'm thinking a wire clothes hanger would work better, so the clothes pins are easy to slide back and forth (almost like an abacus).
Math Coachs Corner: CRA for Composing and Decomposing Numbers. Concrete practice for composing and decomposing numbers from 5 to Differentiate by choosing different target numbers to meet student needs.