I run elastic through the top holes and tie it off tightly at the tip of the fingers and inside of the palm, normal string through bottom holes. with the first iteration of the hand I tied the non-elastic strings in a loop around the bottom of the finger tips but depending on the thickness you use, maybe you can just tie it off at the tip. leave the bottom strings long, when you pull them, the hand closes.*warning* I haven't printed this yet and the fingers are a little rounded so hopefully they'll print alright even thought they don't have super flat surfaces