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).
I could totally do this with money-- dollars on a pumpkin then popsicle sticks with bills and coins that add up to the amount. Addition/subtraction sorting - child needs to determine which sticks add up to the number on the bucket.