We used straws and flexible sticks in different colours (check out the video). You can also use macaroni, wool or rope.
Cut the straws to several cm in length. If the child is older, it can use the scissors to do the cutting (under your supervision). The idea is for the child to put the straws on the sticks that match in colour. You can choose the length. You can make both wristbands and necklaces.